I am hosting on DigitalOcean with Ubuntu 22.04 and Plesk Obsidian 18.0.64. All the domain are using DigitalOcean nameservers. I have one site that is pulled from a GitHub repo. Not sure why that would matter, but it seems every time I pull updates it screws up the email MX records on...
Peter, I was trying to solve the same problem and am also using Plesk Obsidian 18.0.56. When I go to PHP Settings, I see a list of PHP Handlers.
I tried to change the php.ini file using the Plesk SSH terminal. This also did not seem to have any impact.