Mobs don't spawn anywhere besides from mob spawners. I tested a bit to locate the issue.

Step 1 - New world (mobs spawn)
Step 2 - Activate ancient node, the night after the activation no mob will ever spawn (night nor caves)

I tried going super far (10000,10000) from spawn and it doesn't change anything.

I am on Normal difficulty. Chunks load is 12. And the entity cap is close to zero out of 200.

This will be resolved in next major update.

Hi, when will the next major update come ?

Hi, when will the next major update come ?

That update came in May 12th

I still have the issue on my server. Does your fix apply to existing games and also servers ?

I still have the issue on my server. Does your fix apply to existing games and also servers ?

Yes, just use the config to limit the population of sculk units.