KB5005652 - Manage new Point and Print default driver installation behavior (CVE-2021-34481) says:
HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows NT\Printers\PointAndPrint\RestrictDriverInstallationToAdministrators
...
Setting the value to 0 allows non-administrators to install signed and unsigned drivers to a print server but does not override the Point and Print Group Policy settings.
I have tried a clean lab with Windows Server 2019 as domain controller and fully patched Windows 10 Enterprise 20H2 system and this does not appear to be the case. The existence of the RestrictDriverInstallationToAdministrators registry item appears to disable Point and Print Group Policy settings making the alternative mitigations "Permit users to only connect to specific print servers that you trust" and "Permit users to only connect to specific Package Point and Print servers that you trust" not possible.
Is this a bug or am I doing something wrong?