The Chat lines in the Chat window are ordered by time, but when you are chatting in a session that goes over midnight, the chat lines written after midnight are now sorted at the top of the list (since 0:01 is < 23:59), so these lines are not automatically shown, and scrolling up to that new lines seems not to work well, the list is jumping around a bit. Only when the last chats before 0:00 are not shown anymore, the chat window will work fine again. Chat in the car is not affected.
Actual midnight. The in-game chat shows the time things were said, it doesn't sort correctly because it's sorting only by the time instead of an internal timestamp (which would include the date). This was reported on discord quite some time ago.
