The automation will check the conditions right away and just stops when they are not met. It will not wait. Aka, if you trigger on a light going on but have a condition that the light should be on for 10 minutes that can never be true the moment the condition is check the moment the light turned on. Aka, just remove the condition and switch the time offset to the trigger.
For now, no condition is needed because you only have the same condition as a trigger. You may want to add a condition if you add other triggers but it depends on what you would like the achieve.
alias: New Automation
description: ''
mode: single
trigger:
- platform: state
entity_id: light.powder_bath_fan
for: '00:10:00'
to: 'on'
condition: []
action:
- service: light.turn_off
target:
entity_id: light.powder_bath_fan