That is a problem. Clearly not a straightforward one, because we’ve fixed and broken it multiple times. My view is that user-specified values are sacrosanct. When that results in something unexpected, we should address the confusion, not ‘fix’ any user-inputted values.
My favourite premium feature is auto-ratchet, which runs retro-ratchet for me every night. It used to push out my user-specified end date, which was unhelpful for, say, a goal about preparing for an upcoming conference. I thought we’d resolved that, but apparently not completely and consistently. Not least when there are scheduled breaks, an imminent goal date, inter alia.
General note: please let us know on support@beeminder.com when anything unexpected occurs. Even if it’s not strictly a bug, there’ll be something that we didn’t get right. They’re hard to notice because we humans are pretty good at working around quirks in any system and then forgetting that we’re working around something.