Hello,
We are doing some tests with PHP 8.0, Windows Server 2022 and MS Word 2019 and the conversion is done correctly in all cases (without extra time to release the PHP COM instance).
As alternative approach (and a good test), your code could kill the WINWORD process with PHP as detailed on the following reply:
https://www.phpdocx.com/en/forum/default/topic/2438
Instead of using Quit from PHP COM, please test killing the WINWORD process to check if the script ends without adding extra time. It's a very weird issue, we are doing all possible tests in our test servers but we are unable to replicate it.
Regards.