About 20 minutes ago I was able to launch the game, but then I started having trouble fetching my replays and/or saving a paint job.
I then quit FM23, then restarted my XSX, and despite the Xbox dashboard reporting friends playing FM23, all I get is the retry-connection dialog. Have repeated that sequence several times, same result.
The dialog reports the reason as “Failed to download content”
(And yes, all the tests in Xbox OS WRT network pass as normal. Am also able to connect to online things in other games.)