You may be onto something regarding the privacy controls. Is it possible that's what's causing the issue somewhere since it works over VPN; maybe some misconfiguration somewhere?
My current theory is that the problem may reside with scanning/filtering at one of the server hops that is common to those of us experiencing the issue, but isn't present for those that aren't experiencing the problem. This theory fits perfectly with everything everybody has reported so far.
And this is why I asked people about ad-blockers or other Javascript blockers - those products use third party filter lists, same as the various servers involved in forwarding internet traffic between devices.
More detailed explanation...
Every time any of us browses to some website, under the hood, the data packets hop across multiple servers starting at one end (either our device or Rivals servers), then hopping across several intermediate servers, then finally winding up at the other end. There are almost always multiple servers operated by multiple organizations involved.
Many, if not most, operators of these servers employ automated filtering software that uses bad site lists and a bunch of other techniques to block potentially harmful connections and data packets. The effect is the connection requests or data packets arrive at a server okay, but never make it back out to the next server hop because they're filtered out or blocked.
If some content somewhere on Rivals (could be an ad or a user post or multiples of those things) has been flagged as problematic by one of the organizations that are commonly used by all server operators, and is red-flagged, that could quickly lead to Rivals landing on a bad site list and having it's traffic blocked by multiple servers out there.
Normally, when that happens, the origin server admins are notified. But that doesn't always happen. Typically, when it happens to a legitimate site, the legitimate site can find and eliminate the issues on their servers and then contact the organization(s) listing the site as problematic and get the block removed.
I'll look into what I can find out about rivals showing up on any filtering lists. But not all of them are public.
Edit: I should add that rivals.com obviously passes the more well-known site checkers (e.g.
https://transparencyreport.google.com/safe-browsing/search?url=rivals.com&hl=en). But when problems like this arise, it's typically not due to being blacklisted by one of the "biggies" in the filtering business. It's typically due to one of the smaller organizations. There are a bunch of them and we never know which lists are employed by which servers involved in the various server hops involved between our devices and some website somewhere.
Edit 2: For those who know what I'm talking about, I ran a URLVoid check (checks against many of the filter organizations) and it cleared them all. But again, server filtering can employ non-public and lesser-known lists, as well as various other techniques for detecting malicious content. So this is still my preferred theory since it fits with all known facts.