Updated to .200 on night released.

Playing this evening, I noticed a significant lack of natural mob spawning.  It seems to affect mobs from squid to hostiles like creepers, zombies/husks etc.

Boating around a very large area, I saw only a single spawned in squid (I need ink).  I then stopped to dig for a treasure at a large desert island and at night time, I saw a single spider, one witch and one husk.  Normally there would be packs of mobs at night on an island like this.

Similarly, I went to a large nether wastes biome where I'm usually pelted by ghast fireballs...and it's a ghost town.  scanning the area I see only 2 zombified piglins.  No regular piglins, no ghast, no magma cubes etc.  

Went to a nether fortress where I can usually run the halls and fight lots of wither skeles/blaze and other mobs.  Not a single mob is in the fortress...  

Something is up.  Despawn seems to work, I can load up my blaze farm and run away and come back and they all despawn as expected...

Will test other worlds with hostile mob farms and see if rates are noticeably different.