They do not want 3rd party clients to exist which is why they are not doing what would logically make sense: limiting it to Premium.
Reddit Premium exists for $5.99/month, but there's no mention of it for the API changes.
Then you can get an LLM company to easily scrape Reddit for $5 instead of $100000. The main reason for this change is to monetize the usage, not the access.
That would probably kill third party clients because their userbase would be too small.