Thank you Alex. we implemented the suggested change. Reverted privilege to root:root for the conf file, added the missing / on proxy path and verified directory hierarchy as suggested.
Also, went a step further to ensure memory limits in php8.4 ini file was same/increased like that of (older)php8.3, however,
the issue still persists and the update process still throws 'max retries reached' error
Screenshots presented as follows:
Front-end application error after clicking update:

Browser inspect error screenshot on the same page:

Apache Error Log Screenshot:

I do wonder, when we check the systemctl status php8.4fpm-service , 8.4 is the one that is running, however the server log is showing errors associated with 8.3, does this have something to do with the problem we are facing ?
Kindly let me know if there are any further measures/recommendation that we can try or if you think we have exhausted all options in which case we might need online support session as per your convenience.
Best Regards,