After installing Firefox 123.0 I ran a Mullvad Connection check https://mullvad.net/en/check and found I had a DNS leak. Turns out that Firefox had changed the settings under “DNS over HTTPS” so that my Mullvad DNS wasn’t being used any more. After changing this setting to “off” in Firefox, the Mullvad check passed.
Note that this isn’t really a DNS leak. DoH is also going through the VPN proxy, so no data is leaked anywhere here.
What the “DNS leak test” does is to check whether you’re using Mullvad’s DNS servers. That’s it. It doesn’t and cannot actually check whether or not your DNS requests happen through the proxy or not.
In my case the setting stayed off after upgrade.
My Firefox DNS over HTTPS settings are as they were before the upgrade. Maybe this is Flatpak-specific?
I should have mentioned, I am running the Flatpak version of Firefox on Kubuntu 23.10
That should be more secure and private
