Last week I dealt with an issue where my MacBookPro had hundreds of GB of "hidden space" that couldn't be found or removed. (Similar to that person: 100GB+ of hidden space I can't delete or purge .)
Under guidance from AppleCare+, I completely erased & reformatted my entire SSD in recovery mode, reinstalled the OS, reinstalled my data, etc, using TimeMachine. That was completed on Thursday. This morning (Sunday), I get the "Volume hash mismatch" error message asking me to reinstall the OS. (I had had the same message before the hidden space problem and not done anything about it then...)
DriveDX says the health of the SSD is good, 100% overall health rating, 98% SSD lifetime left.
What does this suggest to you? What should I do?