If a person has been arrested 100 times...and this is 101, that is relevant information to me about the likelihood the crime was committed.
A 75 year old man arrested for assault who has never had so much as a traffic ticket in his life is less likely to commit and assault than a 29 year old who has already been arrested 35 times. To me it is totally relevant.
It's questionable whether it's relevant or not. I mean, nobody is questioning whether Floyd was guilty of a crime, nor is anybody questioning the dangerous narcotics he loaded into his system. Passing counterfeit money is a federal offense, and they have the phony bill as evidence. So even if his record were allowed in the trial, I can't see that it would make a difference one way or another.