If you withdraw between the Op start time and 12 hours prior to the Op, your reliability rating will be negatively affected which decreases your chances of being accepted to future Ops. If you withdraw within 4 hours of the Op start time, you will receive a 1-star rating in addition to the decrease in your reliability rating. No-showing an Op will hurt your reliability rating and necessitate a suspension from the platform.
For example, let's say your Op starts at 9:00 AM on a Tuesday. If you withdraw between 9:00 PM Monday night and 8:59 AM Tuesday morning, your reliability rating will be negatively affected. If you withdraw between 5:00 AM and 8:59 AM, you will also receive a 1-star rating.