CBS sent me a reminder email that these past MUScoop brackets are now open for 2023.
https://picks.cbssports.com/college-basketball/ncaa-tournament/bracket/pools/kbxw63b2g42dsojtgy2a====/join?ftag=CBS-04-10add6i&ET_CID=260350&ET_RID=27433688
https://picks.cbssports.com/college-basketball/ncaa-tournament/bracket/pools/kbxw63b2g43dcojqha4q====/join?ftag=CBS-04-10add6i&ET_CID=260350&ET_RID=27433688
https://picks.cbssports.com/college-basketball/ncaa-tournament/bracket/pools/kbxw63b2ha2tgmrxgyzq====/join?ftag=CBS-04-10add6i&ET_CID=260350&ET_RID=27433688
I see this ESPN one is still active also.
https://fantasy.espn.com/tournament-challenge-bracket/2023/en/group?groupID=3001093