Servers collect PHP versions. A panel, a PPA, and a distro package can coexist. php -v shows one. Nginx may use three sockets.
List sockets and Windows handlers, not versions in the abstract. For each, record a vhost or state that nothing references it. Unreferenced units can be stopped so they are not a later surprise. Referenced units each need a fix path.
The fix path can differ. PHP 8.3 might be an Ubuntu package update. PHP 7.4 on the same host might be Ubuntu ESM or a panel build. PHP 5.6 might have no package, which means that vhost is a migration or an isolation decision.
Restart each service you changed. Verify each with its own binary. A single green homepage on the new vhost does not cover the legacy subdomain.
This inventory is the core of legacy consulting: not a slogan that all versions are supported, but a table of which versions have a real package and which need a project.