we haven't done it yet - is fine. It's present tense.
It's when it's used for something in the past that it's wrong.
I actually struggle to make up examples - as I can't think the same way these people do lol
And it's just so absolutely wrong and jarring - my brain just won't do it lol
Next time I hear one I'll make a note.
It's a fairly recent thing - last couple of years probably.
And yes, mainly americans but it does seem to have infected a few brits as well.
Language is like a virus, if you use something enough it infects other people who start using it as well.
Not so much language evolving, as getting a nasty disease