I think I know what is going on. I clicked on a shop to see what it was about. It appears they assigned it to me based on that!
"Thank you for showing interest in completing one of our **** shops. Your selected shop(s) has now been added to your shopper log."
So if you click on a shop to see what it is about they assign it to you?
They emailed me back saying I must have mistakenly applied for it. I've never mistakenly applied for a shop.
You needed to chose a date. I don't think anyone could accidentally choose a shop then accidentally choose a date.