Help! Files are disappearing from my document folders

Help! My MacBook Air 2024, Apple M3 chip (with OS Tahoe 26.5.1) , plus my iMac has been disappearing files from my folders in Documents lately. This also happened about 6 months ago. I then updated the OS, called Apple support, but they didn't know why it happened. Now files are vanishing again., and I can't find them anywhere (maybe they are gone gone?)They are not in trash, iCloud, and I don't have any other profiles. I don't use stacks. I have rebooted my computers. I had Clean my Mac on my iMac, but not used it in over a year or two. My iMac and MacBook are now synced. I have plenty of storage left. I have tried command, shift and period to find hidden files, to no avail. I have saved my current files to EHD's so I don't lose more of them. I did First Aid repair in disc utility. I have not ran Malwarebytes yet. (never used it, just read about it) I called Apple support yesterday and they have no clue why my files are disappearing from my folders. I have changed my apple password, and set up two-factor authentication now. My apple account did not seem compromised though. No strange names on it etc, I feel like maybe there is malware on my laptop deleting items I don't want deleted? Not all files are disappearing, just a few here and there. And not all of the time either. Also, my desktop screenshots all disappeared. Newly taken screenshot are staying on my desktop, for now.