Petrified Amber enemies spawned via spider spawn room

See this video: https://streamable.com/x2vvrw

In that example I had a room where the spiders spawn and climb up to you. The spawn point for the enemies for the Petrified Amber in the next room was also in the spider room. The spiders spawning triggered the petrified amber enemies to spawn as well even though the encounter hadn't been started yet. Once they were defeated the game acted as if I had completed the encounter.

This seems similar to some other issues I've seen, like the "25% chance to open nearby Chests when you Cast as Spell" also can trigger encounters like Cassia. Just earlier today with it on I was fighting a unique mob nearby, yet the encounter started as if I clicked the pump, had the lane/portal spawn near me.