I have a Scrivener project with a large number of .pdf files stored. When I try to copy and paste text from a pdf file into a draft text file I see this gibberish of close parentheses:
Have you tried copying from these PDFs in other viewers? I’m almost certain the problem is with your PDFs, not Scrivener (which technically isn’t even Scrivener, but the stock macOS PDF viewer running in our window). This looks like classic old-school copy protection to me, where the text is littered with invisible garbage characters in between the visible characters.
Do you have a sequence of steps you can provide that would show me how to get this result, if it is using system tools to produce it? I copied the text of one of your posts into a blank Scrivener project, printed the document with Cmd-P, saved the print job as PDF, dragged the PDF into the Research folder of that same project, copied the text again and pasted over the original with no differences in the text.