If the file is located in a /temp/ or /cache/ directory and the timestamp (May 2021) is years in the past, it is almost certainly a stale artifact. However, if this file is in a production environment associated with security software (like Kaspersky), moving it to a "quarantine" folder for 48 hours before deletion is the safest path. Final Thoughts
Associated with Varnish Configuration (VCL) or shared memory logs. 1621058650.vac
file 1621058650.vac This command will tell you if it’s an ASCII text file, a binary, or a compressed archive. If the file is located in a /temp/
While not a common everyday format like .docx or .jpg , the .vac extension is frequently associated with: 1621058650.vac