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 are also forcing it for regular reddit. I get a pop up and when closed you can’t scroll. There is even a thread about what to put in ublock to work around it.
You can just set it to desktop mode. It happens when scrolling on mobile. Or, just stop using reddit altogether