This is really great feedback. Reading this and the other comments makes clear that we need to improve documentation what and why we changed things. All the trk-xxx.iridiumbrowser.de hosts are there to find connections which we were not able to disable yet. All these end up at nothing (404 not found) and are not proxied in any way. Essentially Iridium browser should never contact them - if it does then it is a code path we have missed and a bug.