Reply to a message does not work properly, it doesn’t show the original message or give an indication of what you’re replying to. It only @user notified them.
On web version it will copy the entire message along with the new message you compose. This is also not a great feature even for web.
It would be better if you did it like discord, WhatsApp or other apps where there is a clear division between the original message and the replying message.