But still seems strange to me that so many of my files are being seen as corrupted all of a sudden. Is this due to DevonThink changing its criteria for deciding what files should be locked or not, in the latest update? Or is it due to changes in Apple’s PDFkit?
Your documents aren’t corrupted. The mechanism in DEVONthink is trying to keep your documents from being corrupted. We are making some more modifications for the next release to minimize false positives.
(the on/off links inside the manual itself did not work for me, as it has earlier).
This is a macOS issue and has also been discussed here. (I am adding a note to the documentation for the next release.) If you’re on macOS Monterey or later, Control-click the On link for ForceEditablePDFs. Then paste into the address bar in Safari, okaying opening DEVONthink.