title: flatpak not working - apparently GPG issue
body: <p>On a fresh Arch Linux install, I have difficulties to make flatpak work.
  It seems it's due to a GPG issue but I can't figure out what I did wrong.
  I cleared the caches, uninstalled &amp; reinstalled, to no avail.</p>
  <p>Here is an expression of the symptom:</p>
  <pre><code>$ flatpak remote-ls flathub
  error: Unable to load summary from remote flathub: Signature made Mon Jan 24 18:48:35 2022 using RSA key ID 562702E9E3ED7EE8
  Can't check signature: public key not found
  </code></pre>
  <p>Please note that the user profile has been restored from a backup (incl. its GPG keys). I checked GPG seems functional.
  Any clue?
  Thanks!</p>