Yes, essentially all these deaths are from this surge.That sounds about right. The point is it was not 901 deaths that occurred on on day but rather it was the daily death count plus those that occurred earlier but were not logged.
Florida changed its reporting system in the middle of the surge, knowing it would push back the reporting for the number of deaths.
I have read about many states reporting backlogged deaths after surges. Usually states fall behind when a bad surge is happening. This is the first time I have read about the reporting rules being changed while cases were surging. Regardless, it was common knowledge that Florida wasn't reporting all of its deaths the past couple weeks.