The management of Reddit imposed a very high cost for using its API which was free before. From my understanding most people who accessed it, they used non-Reddit apps to use it (like Apollo & RedditIsFun).
I'm pretty sure it is part of a campaign to dump Reddit to the public via an IPO or maybe SPAC. It is mainly owned by the holding company that owns Conde Nast and I guess they are sick of losing money.
I doubt there is a real alternative unless they do a Tumblr. The large subreddits are largely untouched. I mainly read the economic subreddits and they are pretty much the same (r/wsb, r/economics, r/stocks, etc.)