Make sure they are not vidden under more att the bottom! You can favorite which teams that you want shown straight up! If they are completely gone I would make sure any owner didn’t remove you. Otherwise create a ticket with Microsoft
Used to see this happen awhile back and sign out and in if teams would fix it.
But another possible thing could be that the public groups were configured with dynamic group membership? Anytime this process runs it could be removing users that don’t match the query setup to populate the team.