I am a U1500 bullet player on lichess with >30 bullet rated games. My rating has never gone over 1500 except when it was provisional. Is that enough to keep me out for 7 days?
If not that, then what?
I'm not a moderator / supervisor, but here is the explanation:
The Uxxx tournaments take into account your RECENT rating, not just your current one. In your case, you were over 1500 in Bullet rating on June 11, and that is why you can't currently join U1500 tournaments. I think the timeframe is about 1 week, so if your rating continues to be <1500 for the next few days, you will be allowed to join U1500 tournaments.
Note that artificially increasing/decreasing your rating (e.g. by abandoning games on purpose aka sandbagging) is not allowed, and will mark you as a cheater.
I do not know what sandbagging means, (that is just as well perhaps), but thank you. I didn't know provisional rating counted, but I guess it does.