Bedtime tracks the time in bed inaccurate when waking up early

I’ve been using Bedtime to be able to track roughly how much I sleep. Often it works good enough, but sometimes it tracks my time in bed totally wrong. I know the app is quite basic and therefore I accept that I need to manually change some incorrectly tracked nights. Lately though, I’ve noticed one scenario where I think it would be easy for the app to track my time in bed, but it gets it all messed up.

The scenario:

23:55 - Go to sleep. Set bedtime to 24:00-10:00.

8:55 - I wake up and use my phone for a while. After maybe 5-20 minutes I try to sleep again.

9:45 - I go up, takes my phone with me and can sometimes also use it.

10:00 - The alarm goes off.

My hope is that the app would track the time 00:00-8:55, but what it tracks is something like 9:00-10:00. Why? I can’t remember this being a problem before, i.e. the app correctly tracked the first or both of the intervals when the scenario occurred in the past. During the last months though, the incorrect tracking stated above has occurred more often.