Sorry for your lost ts.
My case also similar but during the peak COVID time in Y2021. Before my dad passed away, we were still texting the night before and it looks the situation under control, but somehow the COVID attacked at mid night about the same timing as your dad, then went in to the ICU for rescue but can't get through it.

So it sounds quite common that COVID bring ppl life away during midnight. I think the hospital has done their best, sometimes we need to learn to let it go.