WTH changing brightness by 1 didn't work, but more then 1 - works

Archive Month of "What the heck?!" (2020)
1

This code works fine:

sunrise:
  alias: Sunrise
  mode: single
  sequence:
  - repeat:
      sequence:
      - data:
          brightness_step: 2
          entity_id: light.sonoff
        service: light.turn_on
      - delay:
          seconds: 1
      until:
      - condition: template
        value_template: '{{ repeat.index >= 124 or states.light.sonoff.state
          == ''off''}}'

And this one stops after one pass:

sunrise:
  alias: Sunrise
  mode: single
  sequence:
  - repeat:
      sequence:
      - data:
          brightness_step: 1
          entity_id: light.sonoff
        service: light.turn_on
      - delay:
          seconds: 1
      until:
      - condition: template
        value_template: '{{ repeat.index >= 124 or states.light.sonoff.state
          == ''off''}}'