I tried to change my cover photo using Facebook mobile app and wanted to revert one of my old cover photos that I used years ago. I went through the cover photos that subsequently appear above the profile picture (cover photos album on my Facebook profile). I clicked the photo I wanted to use, however it was updated as a new upload without retaining its likes and comments.
Then I logged into my Facebook account on my PC and deleted the duplicate and did the same process again. This time my previously used cover photo together with likes and comments was updated successfully without having any duplicate.
What could be the reason of this issue? Is this something common, sort of a bug? My mobile operating system is iOS. I couldn't see either any complaints/examples on the internet with regard to such issue.