Because of how weird this year has been in all sports, the NCAA has decided to grant an extra year of eligibility to everyone who competes in a sport for the 2020-21 season (and for those who, unfortunately, did not compete due to their sport season being canceled). Basketball is one such sport, where seniors could opt to come back in the 2021-22 season if they so desire.
The interesting part about this eligibility ruling is that it doesn’t only apply to seniors. Anyone who is currently on a roster can choose to play this season and not lose a year of eligibility, effectively giving entire rosters a free redshirt year.