Does Editing a Photo Change Its Date?
A good editor keeps Date Taken and updates only the file date. Some tools lose it entirely.
Date Taken records when the shutter fired, so editing should never change it. Serious editors keep it and update only the file's modified date, which is correct.
Simple tools, online editors and some phone apps write a brand new file with no metadata at all. The picture looks the same and everything around it is gone.
Check one before you edit a batch. If a library has already been through something like that, Takeout JSON Metadata Fixer can restore what your export still knows. It runs on your own computer and is free for your first 500 photos.