So, after having studied `lthooks`, `ltproperties` and parts of `ltoutput`, I am still not quite at a point where I understand what could be the reason for the following issue
If I put `\property_record:nn` in `\AtEndDocument`, it won't put anything to the `.aux`. Now, `lthooks` says that `\AddToHook{enddocument/afterlastpage}` should be used to add to the `.aux` file as this is called after all remaining floats or whatsnot have been processed. But ... in my case this still does not work. Only `\AddToHook{shipout/lastpage}` ... I tried to come up with a MWE, but it will still take some tim…