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:

Edit: Best bet now is to use a proxy like safereddit.com.