BENON_ what's your hosting and how did you update the PHP version?
proc_open being disabled is usually a restriction a managed hosting might apply to their servers. If you didn't disable it yourself, then your host did it and their support should be able to clarify/help.
If you changed the version with a switch in a managed panel and this now happens, your host must have inconsistencies between their PHP configuration for the different versions and should look into it. It wouldn't make sense to restrict proc_open in PHP 8 but not PHP 7.
