I'll point out that Reddit runs an onion service (https://www.reddittorjg6rue252oqsxryoxengawnmo46qy4kyii5wtqn...) so blocked exit nodes is more likely to be collateral damage from something else than a deliberate action.

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).