This is honestly very infuriating,
If you create a reply and attempt to post it while it does not exceed the character limit you will be faced with a big red banner warning you about yjt limit. When you close it and attempt to type anything, it will begin flashing again.
On mobile, I am unable to see what I am typing -
This warning shows up everytime you enter a letter, you are unable to see what you are typing until your reply exceeds the character limit.