Files converted to .png after macOS upgrade to Monterey
On an iMac, following upgrade of macOS to Monterey (12.7.4), many files have been converted to .png image format. This includes .jpg, .docx, .pdf and .xlsx files. Dates on the files have also been changed.
This is apparently a real conversion to .png, not simply a renaming of the files.
Does anyone know if this conversion is by design, or due to a bug, or malware - and is there any way back?
Many thanks for any information, suggestions or advice.
iMac, macOS 10.13