To me Reddit is a website, people keep referring to it as an app, but I have never used an app for it. It works best in the browser.
Apollo was by far the best reddit browsing experience on mobile and it seems like the API price was a direct action to shut these third party experiences down knowing their experience was sub par.
Are you using old.reddit.com by chance? If so I have a sneaking suspicious that's going to go away in due time.
Even on desktop, a lot users and mods use Reddit Enhancement Suite (RES) [0] because the "default" Reddit is crap too, lol. I'm sure other HN users would also be using the "old" version of reddit, old.reddit.com [1] since it still performs better somehow. RES has also mentioned that it should continue working fine, but they're not entirely sure about it either. [2]
[0]: https://redditenhancementsuite.com/
[2]: https://www.reddit.com/r/RESAnnouncements/comments/141hyv3/a...
I think the biggest impact, though, is some moderators rely on tools/clients to make their (voluntary) jobs easier. If those tools disappear, then a lot of these subreddits will probably shut down for lack of moderators. And I heard that /r/blind mods literally cannot use the existing Reddit site/apps.
It's best at a desktop with old.reddit and res, but the better apps are a close second.