Unstable soil going crazy on the horizon

[Steel General]

I'm playing 1.16.1 stable, no mods.  I like unstable dirt.

 

On the pre 1.16 stable release I would notice lag spikes in the rain, which I finally figured out were caused by avalanches.  They were typically brief interruptions.

Currently, I'm experiencing lag spikes in no rain.  If I elevate myself I can see patches (maybe 10 blocks by 20 blocks) of dirt dancing on the horizon, popping up twenty blocks in the air and falling again, nowhere near hills or holes.  The dirt settles down as I approach, leaving the typical look of recently-collapsed dirt, sans hillside.