100%, so I have ruled out the browser because I am using the same as yours (maybe just flush the cache to be sure). I have done it on mine and can't reproduce.
I would try connecting from a different internet provider to validate it's not the firewall thing I mentioned on the previous comment.
Thanks @forkyishere, but I still can't log in via Brave.
If you can do it, then everything is fine. It doesn't work for me, but I can work around it.
Humm, I also have that same message in my console, actually, but it continues.
Maybe something to do with Cloudflare location, because that initial error you mentioned (net::ERR_BLOCKED_BY_CLIENT), (I have also) is the browser blocking Cloudflare Insights (performance bench).