Check here: đź’ˇ 5 tips and notes on the recent changes to sharing projects with teams
This threw me for a loop too. Now, when you “change” the team in the “Select a team”, it not only shares it with that new team, but it also remains shared with the original team, which you can see in the “Share” area. If you want to remove the original team, then you now also have to go to the “Share” area and remove the original team from that Members list.