I had this issues on different devices, recently.

On one (tablet with lineageos), Rethink was running and blocked the connection to Mozilla’s Add-on page in its firewall. Allowing Ironfox entries within firewall settings of Rethink fixed it.

On the other device (Samsung smartphone with Samsung branded Android), I first had to search within the security settings for entries that sounded like they prevent the installation of addons within an app and just temporarily deactivated them.

So, beside the already mentioned DNS cobfiguration, you might check firewall settings, if firewall is installed, or go through the “security” settings, if you are on a branded Android.

To get notifications using the Android app on a de-googled phone, you can use the app ‘You Have Mail’ available on F-Droid. It was developed to solve the issue you described.

Dann unter den Einstellungen mal nachschauen. Entweder unter “Advanced” einstellen, dass es automatisch die hohe Auflösung anzeigt oder unter “Data & Storage” schauen ob da eingestellt ist, dass unter Nutzung von mobilen Daten anstatt WLAN die Bilder nur in geringerer Auflösung angezeigt werden.

Öffne die Kommentaransicht und tippe dann rechts oben auf das Bild -> Bild wird in hoher Auflösung geöffnet.