Oh, I guess you mean this then
This was changed a year ago Fixes #36058 - Drop the socket facts chart by girijaasoni · Pull Request #9695 · theforeman/foreman · GitHub, starting with Foreman 3.7 the functionality is not present anymore. I don’t think there’s any plan to bring it back. For the overview of the OS/distribution assignment, one can navigate to Host → Provisioning Setup → Operating Systems and see the counts of hosts for each individual OS.
Similarly, some of the facts are now converted to something called “reported data”, which can be added as a column on the Host index page. Free swap is not one of them today, but could be easily added. That would not work for custom facts though, that was only possible with column_view plugin, which is no longer supported.