This will actually be the night not to forget for Onana, for giving away free two goals to Lyon after the expectation was for Manchester United to win Lyon in the first leg, the second leg at Old Trafford, Manchester United will beat them again.
I think it's unfair to pin the blame solely on Onana. The first goal, two Lyon players tried to make a tap in which confused him. The second goal, keepers make this kind of saves all the time but he was unfortunate Cherki was close by and he pounced on it. IMO, United defense was porous. Lyon was just creating spaces and opening them up. They're lucky Lyon finishing was really poor because they'd have won the game.