Turns out, that act of kindness just helped a good cause ... because Justin Jefferson says he donated the moolah to his local church!!

Of course, giving money to college players is the biggest NCAA violation of them all ... and JJ says he had to meet with the org.'s compliance department to get the situation sorted out.

Jefferson spoke about the infamous incident at the Combine on Tuesday ... saying, "We knew he shouldn't have done it," according to Philadelphia Inquirer reporter, Les Bowen. "It was in the heat of the moment."

The money created a HUGE headache for LSU -- a school rep initially claimed the dough was fake. And then, superstar QB Joe Burrow blew that theory out of the water when he told Barstool Sports the cash was as real as it gets.

LSU self-reported the incident to the NCAA -- and the players involved are not expected to be hit with serious punishment.