Nothing really new, in a sense. Welsh people are still fond of saying 'isn't it' at the end of their sentences. It's a translation of Welsh, where the equivalent of 'isn't it' is used for emphasis, as we might use 'certainly, 'definitely,' or 'indeed', rather than as a simple interrogative. In Welsh it sounds like 'oddi-var', so, at a guess, it's written 'o d'y fa '. Welsh speakers using English sometimes use the Welsh words rather than 'isn't it' .
'Innit' itself is often used for emphasis rather than as a straight interrogative, like' indeed ' or the rhetorical 'don't you agree/think?'.