Azure Devops compare PR shows the file old status after a squash merge

Question

Something strange happened with my branches and PR. So basically I have squash merged a feature branch into my main branch but I forgot to delete the feature branch. A few days later I have recognized feature branch is still in the remote. I remember that I had merged this into the main but I wanted to make sure that there is no unmerged changes and I created compare PR to see the difference. Then suddenly it shows me many files changed which are already in main. It is strange that PR is showing old status of the files on main. For example; below green highlighted version is already the one in main. So main has this nugets 3.1.20 version

here the SS from main

same goes on other files. So why would this PR shows the old version of the file if I create the 2nd time? So it doesnt actually compare correctly?

I understand that older commits can be shown as stated here, not sure if it is the same issue but why file changes or differences should be different doing a second PR?