Sounds like the proxy doesn't work or no longer exists. What DDG goes and changes isn't something Firefox can fix that is up to DDG to provide support for.

More info. It appears that this is a problem with going to 116.0.3 I have kept my W11 system from putting on this update and it doesn't have this problem.

And since we are not using a proxy that FF would know about (we have a firewall gateway server that handles security for our LAN), something within FF changed. Btw - this is only happening on our W10 laptop. It is not happening on our Linux (Suse Leap 15.x) systems running FF (not 116.0.3). So it seems to be something with the upgrade to 116.0.3 .

Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile.