I am getting the same errors on Safari. Clash of Code is allowing clashing but seems to not be posting the results of any clashes / marking participations.
I’m having the same problem with Edge and Chrome. It might be an Adblock or another extension related issue. I found a way to circumvent this. Just copy the URL of the puzzle you want to do in a new tab, say this one. During the stuck loading, delete your browser’s Codingame cookie, and refresh the page. You should now see the IDE and be prompted to log in again with a pop up. Log in and you’ll then be able to start coding afterwhile. You should save your code in Notepad++ before submitting though, just in case…