The long enduring pressure against Floyd's neck by police officer Chauvin was the cause of him blacking out and eventually dying.
What you're saying is "if the media representations were accurate, then ..."
Which is why there is an actual trial, not a "trial by media" which the very phrase's existence is an admission that the media version is likely unfair and inaccurate.
As I said right at the start - if you are going off the media reports of the trial you are seeing a completely different trial than if you follow it yourself and you're likely going to be surprised with the outcome as a result.