After installing the July 2021 and later updates, non-administrators, including delegated admin groups like printer operators, cannot install signed and unsigned printer drivers to a print server.
Security updates released on and after Jcontain protections for a remote code execution vulnerability in the Windows Print Spooler service ( spoolsv.exe) known as “PrintNightmare”, documented in CVE-2021-34527. KB5005010: Restricting installation of new printer drivers after applying the Jupdates Summary