Plugin reported as installed after removal

Problem:
Disabled foreman_plugin_proxmox and uninstalled ruby-foreman-fog-proxmox. After both actions are performed, the About page still shows incorrect information: Available providers says Proxmox is installed, Plugins says I still have foreman_fog_proxmox version 0.16.3 installed.

Expected outcome:
Proxmox plugin should be shown as not installed

Foreman and Proxy versions:
Foreman and proxy 3.12.1

Foreman and Proxy plugin versions:
ruby-foreman-deface/plugins,now 1.9.0-2 all [installed,automatic]
ruby-foreman-maintain/focal,now 1.7.6-1+ubuntu2004 all [installed]
ruby-foreman-puppet/plugins,now 7.0.0-1 all [installed]
ruby-foreman-remote-execution/plugins,now 13.2.4-1 all [installed,automatic]
ruby-foreman-salt/plugins,now 16.0.3-1 all [installed]
ruby-foreman-tasks/plugins,now 9.2.3-1 all [installed]
ruby-hammer-cli-foreman-puppet/focal,now 0.1.0-1+ubuntu2004 all [installed]
ruby-hammer-cli-foreman/focal,now 3.12.0-1+ubuntu2004 all [installed,automatic]

Distribution and version:

Other relevant data:
Foreman host is an Ubuntu 20.04 machine, 3.12.1 is the last version compatible with 20.04. It started as a 3.5 install and was upgraded from there. In the above reported state both the About:smart proxy and compute resources tabs continue to spin forever (never load with info), re-enabling foreman_plugin_proxmox (which also reinstalls ruby-foreman-fog-proxmox) appears to fix that

I can’t comment about proxmox specificly, but AFAIK there is no way to uninstall plugins that will have them clean up the DB on the way out. Therefore it is expected you will still see plugin data in your instance. I imagine this is such a case.