Rocky Linux uses PrivateTmp to give each process it's own walled off section of
/tmp/. This is good for security sometimes, but it also lead to frustration because files written to
/var/tmp/ will not show up when you need to debug something. To disable PrivateTmp for php-fpm you need to modify the systemd configuration for php-fpm. This is done by running
systemctl edit php-fpm and adding a section that says:
Once the change is in place you will need to
systemctl daemon-reload and then restart
systemctl restart php-fpm.
Note: Borrowed from Stack Overflow.