Twitter's infamous token limit removes Flamingo from Play Store
A screenshot from the unpublished Flamingo client.
There have been numerous other cases of these third party apps dying off due to the token limit reaching back to 2013. There are a few who made it back, such as Fenix in 2016. Twitter basically allows only so many "tokens" for each developer, which caps the amount of users each app can have. These tokens also account for anyone working on the development of the third party app as well. Developers are able to recover tokens from accounts that are no longer using the app, but the number of tokens stays the same. Many who are in favor of using third party clients claim this practice is unfair, since it limits the success of developers and allows Twitter to keep the majority of users. So unfortunately, the better the app and the more success a developer has, the faster the app is killed.
via Android Central
Things that are NOT allowed: