Certainly in NYC, I recall that at the worst of the first wave, excess deaths were very correlated with registered COVID deaths and they spiked simultaneously. There were fewer registered COVID deaths than excess deaths, but during the first spike testing wasn't always done, and people who died at home didn't always get a test postmortem.
When there's a COVID spike, most of the excess deaths are people dying of COVID (some might be people dying due to fear of COVID, or hospitals collapsing- arguably still "COVID fatalities" even if they don't test positive).
When there's a COVID spike, most of the excess deaths are people dying of COVID (some might be people dying due to fear of COVID, or hospitals collapsing- arguably still "COVID fatalities" even if they don't test positive).