I keep my illustrator on auto-update and have checked to make sure I'm up to date. Since the most recent update, files I saved before the update as an AI-editable PDF will not open as vector in Illustrator, and I get this error, suggesting the file was made in a newer version of the software (which is impossible). This is a pain because I have hundreds of files like this that I can no longer open to make edits before they go to print.
I just tried that with a document created in Illustrator 2021 and that worked.
So for you it's happening with documents created in 2023? I don't save editable PDF, but I save AI files. Can you please upload a demo file that causes this issue for you? Dropbox or the like would be fine.