Looks like the Big 12 will be back to 12 when Texas and Oklahoma leave.
apnews.com
BYU will start conference play in 2023, with Houston, UCF and Cincinnati no later than 2024.
The conference will also return to having 2 divisions.

Bigger Big 12: BYU, UCF, Cincinnati and Houston on the way
The Big 12 has added four new members. BYU, UCF, Cincinnati and Houston have formally accepted invitations to join the league.

BYU will start conference play in 2023, with Houston, UCF and Cincinnati no later than 2024.
The conference will also return to having 2 divisions.