Maybe worth mentioning: I have a recent version of openHABian (in a vm) and don’t have any issues, but I have frontail version 4.9.0, the most recent version is 4.9.1 from March 26, and it has a fix to support RPi.
I checked the versions as you wrote and found the following results.
In my running productive system the frontail version is 4.8.0
in the new system which I built up from the scratch, based on the image openhabian-pi-raspios32-202007302224-git0290f04-crcd2852e99.img.xz the frontail version is 4.9.1