This is no error but only a information about a changed file.
As there is no openHABian 3 yet (see https://github.com/openhab/openhabian/releases/tag/v1.6.5), I guess you are talking of openHAB3. But which version? There are at least two official stable versions and many Milestones, not to talk about unstable versions. All of them could be installed thru openHABian (depending on when it was installed).
The symptom (openhab.service changed) is a rather old one, afair there was something with ZRAM involved, but that’s only guessing, and the issue was solved months ago.