can confirm
doesn't need new server. Just go far out in the nether
confirmed for 1.16.3
this also occurs on seed -4977636324086404853 at 49, 71, -79, on 1.16.3
they are different. MCPE-95435 is about the slime, MCPE=95434 is about the observers.
what is the tick speed set at?
I think this is "works as intended"
restart the server (turn it off and turn it on again)
what is the affected worlds file size? Perhaps the world is too big for your console.
check task manager to see if there are big programs sucking up all of the CPU/GPU