In my experience, when you’re within 24 hours or so of an upcoming renewal, you have to contact support to stop the renewal. And there isn’t a prominent way to contact support, because the contact form is hidden until you view a past order. That’s not really an edge case…
On another note, an actual edge case that happened to me is that I was in a different country when my Uber One was about to renew, but I had no way to cancel because the app kept geolocating me and displayed a UI specific to my visiting country. I got no Uber One benefits in that country anyway. So I had to send an email to stop renewal, and while I was waiting for a reply, I got charged. Support said they can’t refund me, and I ended up having to do a chargeback.
On another note, an actual edge case that happened to me is that I was in a different country when my Uber One was about to renew, but I had no way to cancel because the app kept geolocating me and displayed a UI specific to my visiting country. I got no Uber One benefits in that country anyway. So I had to send an email to stop renewal, and while I was waiting for a reply, I got charged. Support said they can’t refund me, and I ended up having to do a chargeback.