I think the only problem to crash it are emojis. It works the same on smartphones. Too many emojis and your app crashes, but I think there shouldnβt be a limit on charachters like in ts3, just limit the emojis.
Flooding is sending lots of messages, the only thing can happen with a long message is βclearingβ the chatβ¦ maybe it can be useful to delete that messages manually for you if they are disturbing you