I had a look at the other two servers I have ESET installed on. The only difference is that a CIS hardening policy is applied on the machine that is having problems.
Current product version: 8.1.813.0
I'm using the CIS security policy for Red Hat Server Level 1.
Try installing a fresh copy of RHEL 8.5 with that policy applied during install (Can select it in the policy section).
It requires that /var/tmp, /tmp and /home are on their own partitions.
I'll install a fresh copy of RHEL 8.5 without that policy later on tonight and see if I get the same problem.