Calling "turn_on" with a brightness attribute of 1, lights turn on closer to 50% brightness while showing brightness=1 in UI

Configuration
1

This is something weird I noticed after moving from Docker and deCONZ (if that matters) to hassOS and ZHA:

If I turn on a light via automation (AppDaemon in my case, but also if I just do from service call in Developer Tools → Services), I can’t turn on at low brightness (brightness=1). If I try, it turns on significantly brighter, closer to 50%.

The extra weird thing is that in the UI, it shows that it is on at brightness=1, but if I “increase” that to brightness=2 with the slider, it dims to almost nothing (so actually setting the brightness to 2).

service: homeassistant.turn_on
data: {brightness: 1, kelvin: 2200}
target:
  entity_id: light.kitchen_spot_5

(the exact same happens if I use service: light.turn_on)

So if I click “Call Service” with the above code, it turns on at ~50%, while showing 1 in the UI. If I click “Call Service” again on the same code, it actually dims to brightness=1 (or at least what looks like it).

Why the heck does it do that? And how to I stop it?