I posted a quick update on the issue on github. It hasn’t been quite long enough to call this solved, but updating Virtualbox from 6.1.32 to 6.1.38 has resulted in HA running for the last 20 hours. This could be a fluke, but wanted to add it here in case someone finds it in the future and I forget to come back to post another update.
UPDATE: So, it’s been 2.5 days now without a crash. I think this is solved 