I had same issue for the past 3 months. Both after and before upgrading to BigSur. I am still testing, but it would appear that in my case, OneDrive that failed to reconnect was the culprit. I removed it altogether (disconnect the account followed by removal in the applications), and so far, my mac seems to be holding up in situations where it would have already crashed. So looks like pruning those background apps which are on all the time might be a solution.
AntonB-30
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