Without a logged-in session, I can only see error messages which change randomly. Most of them seem to be either an IP range blocking page or an image with "You broke reddit" message on it.
What a terrible experience.
I guess at least 50/50 it's an anti-abuse measure (rather than surveillance capitalism), at probably some human cost of denying reddit as a venue/channel to oppressed people.
Incidentally, if anyone is using Tor in ways that show up as significant abuse to Reddit, that's hurting Tor for those who need it for more legitimate purposes.
Generally speaking, if you're getting blocked (from old.reddit.com or otherwise), the workaround is to login. If you're logged in and still getting blocked (or are getting blocked trying to login, that's a different problem entirely).