Light always goes to full brightness before turning off

I have a 3 Gledopto Zigbee bulbs, grouped as a “helper” entity. When I turn this group off using light.turn_off service, the bulbs go to full brightness for a moment and then fade off. I’ve tried setting transition to 0, and also unchecking the transition box, but it’s the same either way, the fade out takes about 3 seconds. Why does it do this? I don’t see anything in the logbook that would explain why it goes to full brightness.

Do they do the same thing when you turn them off individually?