Not sure if this is a bug or a feature request, but I have a few PDFs for which any selected or copied sentences are mashed together (“sentenceslooklikethis”). When I open the same PDF in another app, such as PDF expert, the text is copied properly (“sentences look like this”).
(As a tip to others with the same problem: manually inserting spaces in a copied paragraph is one of those tedious tasks that ChatGPT handles with aplomb in my testing.)