Based on your posts in other threads, I know you are serious.
Here is my list of bugs and observations I’ve compliled so far.
Custom and ranked adventures missing, a major regression from FH4.
Arcade events requirements are often too demanding, they should be lowered / scaled to the number of players and the time limit raised to 15 mins. (Or keep it at 10 mins and lower the requirements even more.)
Still can’t skip the game’s lengthy splash screens which are also still too loud. Complained about for 3 years of FH4, never fixed. Unlike FH4, alt-tabbing while this noisy chore completes does not mute the sound when the game window isn’t in focus.
Launch control makes some cars sluggish and unresponsive for a few seconds, this feature does not work well and should have an option to disable it entirely, just like with other assists such as traction control.
Can’t skip cutscenes in stories, this was a common complaint in FH4.
In stories, some of the requirements are ridiculously easy, so you can cut out a large part of the course and just drive directly to the finish, to a much larger degree than you could do in FH4, exceeding the 3 star time by a minute or more. But some of the other story tasks are very hard even for a skilled player. Vocho In the Baja requires driving perfectly and taking a specific shortcut, and even then you only finish it with barely a second to spare. Clearly not well tested.
Even on a fast PC with the game installed on SSD, the game has multiple short loading screens. The Series consoles apparently do not suffer from this, in which case it appears that PC users get an inferior version of the game which assumes the game could be installed on a slow hard drive, so takes the time to load a loading screen first, which increases overall load times unnecessarily. Sometimes the time to load the loading screen is equal to or greater than the subsequent loading. Everything from photo mode to going to the garage has loading screens or black screens / spinning circles everywhere. On a fast PC with a lot of RAM etc. this is just a bad design and it could have been significantly streamlined.
Can’t control volume of cutscenes, speech or music except radio. Most speech is not affected by the speech volume setting. The streamer mode still doesn’t disable that music either.
Radio regularly turns itself on, this never happened in FH4.
Radio ‘please change back to streamer mode’ bug when a skill song is playing (after the radio has turned itself on), even though you are already in streamer mode.
Missing graphics windshield reflection quality setting that FH4 had. FH4 let you disable this effect entirely, FH5 doesn’t.
Mouse pointer doesn’t hide when using controller, which it did in FH4.
Game is too dark in certain lighting conditions, much darker than FH4 while using the same default brightness setting of 50. If you turn it up to 70, it fixes that problem but then is too bright for most of the time when the game is in daylight.
When you choose ‘get in car’ from free roam, it still asks if you want it delivered to you. Redundant step, of course I do. Issue never fixed from FH4.
Replays not improved from previous games, still poor compared to competitors. No auto TV camera type option.
Syncing FH4 liveries took 45 minutes. Microsoft’s cloud saves still operate at a snail’s pace. ‘We should be done soon!’ is wishful thinking.
Importing FH4 liveries and vinyls must be done laboriously one at a time, no option to import all, or a tick box system where you tick the ones you want and import all those at once.
In Rivals, still no way to change car or tune without laboriously quitting back to free roam first.
In Rivals, bug where after you beat a rival’s time, it subsequently shows you the next rival as the one you just beat.
In Rivals, in ‘my rivals’, if you delete them too quickly, the game crashes to desktop, confirmed bug on PC and console which still exists from FH4.
When choosing a paint from your designs, it still doesn’t show you designs for the car you are in first, you have to manually scroll and identify the compatible ones yourself visually. This is something which works properly in Forza Motorsport 7.
When using fast travel, returning to free roam or changing cars in free roam, still have to wait for a camera panning animation to complete before you are allowed to use the menus or drive the car, which effectively doubles the loading and waiting time for no good reason. Using fast travel during arcade events to save time, like doing repeated jumps, is hindered by this baked-in delay where every second counts. Bad design.
When you fast travel to an event, race or story, sometimes there is no prompt to start the event. You may have to drive forwards some distance, and then the prompt will appear behind you, requiring you to reverse back to it.
‘Saving’ spinning circle sometimes never goes away until you exit an event and restart it, same bug from FH4 still present in FH5.
Can’t zoom out on the map enough to see it all at once. Old games like Test Drive Unlimited let you do this.
When selecting a speed zone or trailblazer on the map, a big text box covers the route or destination so you often can’t see where best to start it from.
Endless nag screens. If you’re in Horizon online and it disconnects, you can choose Horizon solo, but then it will bug you to ask if you want to go online instead. Whatever you do, it never leaves you alone for long.
Crowd still animates at 30fps, regardless of the framerate the game itself is set to.
Eliminator still tells you the destination distance by road rather than as the crow flies, which would be much more useful in a game where taking a direct route is often required. You can be very near the destination but it might say you are miles away.
Eliminator still begins while blocking your view with a big message, and doesn’t display your HUD, meaning you are disorientated and can’t see if there are car drops or opponents nearby and are vulnerable. Never fixed in FH4 either.
Super 7 challenge cards can still appear in a language different to your own, an issue never fixed since FH4.
Rewind is still broken from FH4, sometimes it won’t let you rewind after a certain number of times. This is a hindrance to hitting some bonus boards which require trial and error.
PR stunts refuse to register a time if it is too soon to the previous one, it insists on showing all the many notifications first before it will register any subsequent attempts. This annoyance persists from FH4 and means rewinding to do it again is impossible.
PR stunts have a bug where you can beat the requirement, in the correct car, but it says you are 1mph or 1ft short.
Seasonal goals have a bug where it might tell you to win an event but in fact you need to come second, or it tells you to do a clean rivals lap, but actually only a dirty one works.
If wheels are turned before taking a photo, wheels revert to straight ahead during photo mode. This worked in FH4, now broken.
Online races no longer show split times, a major regression from FH4. Also, game stats don’t keep track of your number of online race wins any more (except Eliminator).
Eliminator problems include invisible players, inability to challenge other players and the finish line not registering when you drive over it.
Custom controller settings insists you assign a button to the map, an annoyance which remains unfixed from FH4.
Forza Link is a regression over the old chat system because it only allows two custom chat phrases rather than four. The two it chooses for you tend to go unused because they are generic things like ‘Hi’. In a race it would be fun to have a mix of phrases which were banter, to apologise for a mistake, to acknowledge good driving, or to say GG at the end for example.
Other players can no longer see your ‘prestige’ level on leaderboards, rendering ‘prestige’ pointless because you appear to be a lower level player than people you are actually higher level than.
Route creator has significant failings and limitations. https://forums.forza.net/turn10_postst169800_The-state-of-the-track-map-event-challenge-editor-is-just-embarassing.aspx
And https://forums.forza.net/turn10_postst170585_Route-Creator---Blueprint-is-effectively-unusable-for-people-putting-a-lot-of-work-into-tracks.aspx (horror story)
Seasonal PR stunts no longer give super wheelspins, only normal ones, a regression from FH4.
Weather bug where it can be stormy, dark and wet one moment but then dry and sunny instantly the next.
At the end of a race you have to wait five seconds (baked-in delay while the screen blurs for dramatic effect) before the scoreboard appears.
In cross country, there are green flags near checkpoints which are not much different in colour to the checkpoint markers, which can be distracting and cause you to miss a checkpoint.