It argues that the primary cause was a drug overdose and the secondary and minor cause was the way the police handled the situation. It is clear that Floyd was having overdose issues prior to Chaven putting him on the ground and a knee on his neck. Watch the whole arrest video, not just the part where Caven is on his neck. It is, or was, available.
The police start by questioning Floyd. They then arrest him. He resists. They get him cuffed after a struggle. Floyd is having trouble breathing and is acting highly erratically. They finally manage to get him in the police car back seat where he starts having more issues. He is removed and continues to struggle with the police. Chaven puts him on the ground and the knee on his neck. Paramedics are called and on their way. Floyd continues to struggle but is clearly starting to become less and less able to respond. He dies.
That's what happened. Floyd committed at least one, and probably several, felonies to get the attention of the police. He resisted arrest. He was overdosing on a dangerous drug. The police did as their training recommended. Floyd died. The overwhelming majority of that is 100% on Floyd, not the police.