After upgrade to 3.0.3 and PHP 8.0.28 the page id number is printed on frontend

After upgrading our company website from modx2 to 3.0.3 the id number of each page is printed on the page just before the /body tag.
When using plugin Emo the id nr. was placed between the Emo scripts, but removing Emo resulted still in showing the id nr.

you can try to deactivate all MODX tags in your template. Add a - after all opening tags

Then reactivate all tags one by one and check, when it starts to show this id.

Hi Bruno, thanks for your reply. Working on my templates made me aware that there are more issues: chunks with scripts cannot be saved and also snippets cannot be saved. Could this be a modsecurity issue?

I found the error showing the Id nr. on the frontend. Bruno, your suggestion to reactivate the tags one by one did the trick.
[[*id:input=`… , in combination with a LinkedIn script that was no longer in use caused the problem.