Pillagers spawning underground underneath a pillager outpost at -50

What I expected to happen was...:
Pillagers to spawn above ground, close to the outpost

What actually happened was...:
The pillagers spawned in the deepslate caves, well below the outpost

Steps to Reproduce:
1. Go to an outpost, and go underground
2. Make sure you're not in spectator mode
3. Pillagers will spawn underground