Import data can create empty revisions

I can't describe reproduction steps but I noticed that the "import data" action can lead to empty revisions.
See for instance https://www.xwiki.org/xwiki/bin/view/SecurityAdvisoryApplication/SecurityEntries/GHSA-wvpm-gcqh-7g4j?viewer=changes&rev1=1.1&rev2=2.1&

Revision 1.1 is me importing the advisory a first time, revision 3.1 is me importing again to synchronize with changes I did in the description in GH.
But I can't explain the 2.1 empty revision, maybe a scheduled task that re-imported the advisory, leading to an empty revision because the advisory wasn't changed in the meantime?