The cursor is always placed with a +1 offset to the character it's standing on.

Example:

On the screenshot my cursor is between l and ock but in reality it's just before the lock text.
The same effect happens when the cursor is on the end of my message:

It seems like there's a whitespace after my ! but in reality there's no trailing whitespace. it's the cursor being offset again.

Thanks for taking the time to look into this issue!