Right, I missed where the dev said:
More importantly this code will unfortunately likely never be merged due to legal issues
Public instances will easily hit the 100 requests per minute restriction on the free tier. Some apps like RedReader are exempt from the new restrictions, I wonder why they can’t use their API keys in the meantime but maybe it’s more complicated than that.
The dev got an exception from Reddit until they get their subscription up and running. They posted this on their subreddit.