Tried on AlmaLinux 9 (1:1 copy RedHat EL 9) and it is same:
Agent installation fails with "Error checking peer certificate: NOT_VALID_PFX" too
Eset Antivirus (EEA 9.0.5) - can be installed (el8 rpm) on EL9 but eea.service dies with crashdumps
There is compat-openssl11 package on EL9 linux, but instalation of this package does not help in this case.