[Bug] The number of pdf objects was changed after deleting the tag

[thaiminhlien]

Hello,
There seems to be a problem in the process of deleting the tag.
I did some tests by just opening the file and reading the number of pdf objects in the file, printing it to the console screen, deleting all tags, then checking the number of pdf objects again.
I noticed that the number of pdf objects has changed and the values in some pdf objects have also changed.
Please see the image below or my project.
Please check, thanks.
https://github.com/thaiminhlien/pdfix.git