As of a few minutes ago old.reddit.com now seems to requre logging in to access it.
Shame as it was still the best place to browse for info about some niche interests.
Edit: Seems like they might be testing the change as it is hit or miss at the moment.
Edit: Adding this to My flilters in uBlock Origin seems to fix the issue for the time being:
||reddit.com^$header=referer:
They’re rolling it out piecemeal. I don’t think they’ve rolled it out to the UK yet, for example, because I can see both old and new interfaces without it requesting a login, but clearly it’s requiring login for some people, somewhere.