I created a custom resource and did the publication. It all worked fine (there was a warning in the logs at this time too). I then redrafted it and it got successfully deleted too with same warning in the logs as below:
I have not experienced any issue but this warning is now appearing every time during publishing so I wanted to understand what it is, it's impact and how to fix it?
I was able to resolve this error. I went through previous publication logs to see when did this error started coming. I checked all the changes that happened in that particular publication where this error first appeared and noticed extensions in oob resource. I redrafted that resource and did another publication and the error was removed.