Chauvin may be racist. It's certainly possible. He has some suspicious incidents in his record. But it's just as likely he's one of those aggressive, action-hero wannabe cops who used to bully kids when he was young. His bias may be that he's looking for an excuse to dominate those who break the law. That's what the commendations on his record for bravery suggest.
Racism is irrelevant in the sense that it doesn't explain why the murder happened. It makes for a lazy analysis. The main bias in American police forces is based on class, not race.
Police go after petty criminals who are typically poor, not white-collar criminals who are typically white. African Americans are disproportionately poor and therefore involved in petty crimes. Policemen aren't known for their subtlety or for being bookworms. They're often belligerent and looking for an excuse to "blow off steam," like in the action movies. That means blacks are going to show up on their radar. Nothing as esoteric as white supremacy is needed to explain the numbers of poor blacks killed by cops, especially when the cops are busy shooting plenty of poor whites.
And needless to say, throwing around the term "racist" is very lazy and irresponsible. It's a wokester habit that speaks to the grave weaknesses of that standpoint, as shown in the article below.