Is the traffic encrypted?
If it is, look at the certificate. Which hostname is it for primarily? Which SAN (Subject Alternative Name - basically a list of all other hostnames the certificate is valid for) are set, if any? Which Certificate Authority issued the certificate or is it self signed?
Imagine getting a 404 or 500 error. Then archiving that on archive.org (and screenshot that dialog on steam) and accept the terms. If there’s any problem and they say you violated the EULA, point them to the terms you accepted.