It's notable that part of the size is clemency for people serving long sentences for marijuana dealing. I actually have mixed feelings about that because I don't think it's as simple as oh there's somebody spending 20 years in jail just because they wanted to smoke up. I think there are a lot of good reasons why people were convicted on what were primarily marijuana charges but I won't go into that right now.
Notably there are some pretty bad appearing people in the clemency and pardon categories. I don't see any excuse for the commuting the sentence of the judge that sold kids into private prison for money. He should be on death row for that sort of thing. I also am very sure that Biden did not review this many cases which might be unlawful delegation of executive duties.