It seems it's a compromise time after a dispute between BBC and ITV.
BBC wanted 3.00 as it wouldn't impact Doctor Who and Eurovision.🤣🤣🤣
ITV wanted later as it maximises TV advertising revenue.
So it's a compromise time.
That's a quick Google by the way as I wasn't even aware the Cup Final was today until yesterday , who was playing and only knew the kick off time reading this thread.
So different from childhood getting up early to watch all the build up and the game.