You might be able to locate the original Pages document on a previous Time Machine backup with /Applications/Time Machine, or through the use of Spotlight. In System Preferences > Spotlight > Search Results panel, do you have Documents selected? From the menu extras part of the menu bar, use 🔍 and enter the following syntax choices:
Locate the Pages document created between two dates, or modified since the first of the year:
kind:pages created:06/01/2021-01/29/2022
kind:pages modified:>01/01/2022
Alternatively, if you have access to MS Word v16.31 or later, it will open that PDF and allow you to convert it back to .docx. Then you can open that .docx in Pages and avert copy/pasting.