Interesting. From some googling it looks like America is a mix of both but leaning towards day-ta, whereas the other countries are more consistently as I said.

I have a British friend who now lives in Canada and works in tech and has changed the way he says it (from day-ta to dah-ta, or really more like dah-da) for convenience. I had thought that it was an Atlantic divide but seems like there’s more to it.