A leaker, don’t remember which one now. Was awhile ago, like back when they were first announced.
There originally being PS4 and X1 versions isn't surprising I suppose when you consider when the game was first announced.
Other 3rd party exclusives releasing this year also have PS4 versions, so I'm not sure it follows that that this wouldn't if it wasn't possible.
But regardless of the truth, I wonder if MS would even release a theoretical X1 version in 2022. I'm curious to see what MS does on that.