If the ball enters the hoop from below and passes back through the hoop, it doesn’t count as a basket. It’s a violation and the ball is given to the other team.
From the NCAA rule book (Rule 9: Violations and Penalties, Section 6, Article 1):
“It is a violation when a player intentionally kicks the ball, strikes it with the fist or causes it to pass through the basket and enter the cylinder from below.”
This play occurred in a second-round game during the 2023 NCAA Tournament. In the first half, Michigan State tipped the ball – after a missed shot – up toward their own hoop.