This suggests that my opponent effectively won but owing to a howler lost. It’s neither a fair nor accurate way to report a game.
I looked at one of your games. It seemed accurate. You were down a pawn. I don't know if you were losing but the computer thinks that white has a 1.8 advantage.
Then your opponent hung his queen.
Qc4 should have lost his queen to Bxf2+..
But you didn't see it and instead took on a3.
Crisis averted. Did he trade queens and then retake?
No, he retook on a3, leaving the queen hanging again.

You took it and won. The one player was winning but blundered it away seems accurate.
If the Game Report points out a few of these things, you may start to look for them.
This suggests that my opponent effectively won but owing to a howler lost. It’s neither a fair nor accurate way to report a game.