Ok, now things are getting interesting. An ASCII value of 0? I’ve never heard of that. I honestly didn’t know it was possible. As it happens, yes, it’s a real value and in SSMS it does a few strange things.
In the comments Denis Gobo is right: the 0 byte is the null terminator, which should appear at the end of a variable-length string to indicate that there’s nothing more to read there.