@snow

It's politically complicated. The developer of Mastodon opposes instances using limits other than 500, so unmodified Mastodon treats 500 as a law of nature - by design, the API doesn't have a way for the server to tell a client differently.

QOTO is modified to allow more characters, but still lacks an official way to advertise this to Tusky. Some instances have unofficially extended the API to do so, and it sounds like QOTO may soon follow suit. Until then Tusky assumes the limit is 500.