Compatibility Checker Keeps Activating?

Essentially, as the subject says, I have XLSX & XLSM files that continually pop up with the compatibility checker. If I uncheck it, it stays gone for the day but appears again the following day.

Everything I've found online says to use XLSX to avoid it, or convert the files, but I don't see this option. Is there a way to fix this so I don't have to continually face these pop ups?

I'm using version 2508 (company owned, so I can't control this) Build 16.0.19127.20570

For further clarity, these files are also uploaded on a shared drive, so I'm not certain if that is the issue or not.