European?
I've had the same issue on my Android/Chrome over the last month, and before that it was iffy if I could access anything on the site as their privacy pop-up wouldn't let me click to accept or deny it. Then one day it did, and ever since I've had the bad request page. I get my laptop out once a week or so and here I am.
I'd been in contact with support over the issue, and the best they could ever do was tell me to use another browser on my phone. That wasn't exactly helpful. They've ignored me since the whole bad request thing kicked in.
It actually pisses me off, to be honest. I've been on this site for 18 years and to just lose access over something that most legit websites with the traffic of this one would have fixed in hours is frustrating and idiotic.
You can try making a thread in Support. Maybe things will be different for you. But don't be shocked if their answer is for you to try Firefox or something.
And if you do find a solution that doesn't involve changing phone browsers, send it my way. I'll do likewise.
Good luck.
/threadjack