A naturally spawned beenest nearby starts pumping out bee pokemon as soon as I get within spawning distance. It appears to spawn with each tick or so, based on the popping sound and how quickly the area fills with pokemon.

According to Kadinu's testing, not every beenest will result in an explosion of bees. (they had to place four hives before getting the effect I experienced.)

Hello! I originally tested it when I wasn't part of the support team yet but now I've tested it again. The issue still happens on 9.0.4.

I tested it by using "/give @s beehive{BlockEntityTag:{Bees:[{EntityData:{id:"minecraft:bee"}},{EntityData:{id:"minecraft:bee"}},{EntityData:{id:"minecraft:bee"}}]}}" and placing down the beehive. Upon the third hive placed the bee explosion happened. I've also tested it with the bee nest block and with 1 and 2 bees per hive and the same thing happens. although not always the third placed one.

Thank you for your report!

Moved to an internal.