There are two autopsies
One says asphyxiation (the independent one), but there is no real evidence he died of asphyxiation beyond that video.
The actual medical examiners report says he died because his heart stopped beating, that was exacerbated by "neck compression", the rona, and drug use. And i'm sure stress although i don't think the examiner mentioned stress.
Certainly what that cop was doing would not have killed Floyd had he been sober and rona free that day. He did not get strangled....His heart stopped working
Now you can blame the cop. But let's not pretend Floyd got murdered. He probably wasn't. We're doing this for other reasons not because Floyd deserves justice for a very normal police interaction.....And I think it should just be the one cop not all of them. If he wanted to be treated with kid gloves he could have been more compliant