It is incredibly simple to glitch the signature field even when the field itself is set to be a requirement. Simply open the field, lightly tough the screen ( no need to even make a visible mark ) and the words "Sign Here" vanishes and the filed accepts your "signature".
In my line of work - a signature equals payment. This glitch is affecting our bottom line and is FAR TOO EASY to push through. I have a video of this glitch, which I can not upload to this file as it is too large, however I have emailed it to tech support and my POC.