Yup, it's a VPN. If I turn it off, it works properly even in the same browser (Mullvad). But I refuse to cave in, so if they every start checking for VPNs even in the old Reddit, or disable it altogehter (which I'm sure will be soon, since you can also use it to bypass "Log in to see NSFW content"), I'm out for good, and will finally block Reddit at my Kagi.