When Alexa mistakes something I say in my house, nine times out of ten, it results in her thinking I requested some sort of music to be played. Even though I almost never purposely ask her to play music.
I noticed the shopping suggestions as notifications some time ago. It doesn't happen to me that often, but since shipping/delivery notifications are the only type of notifications I'm interested in, I delete any without listening to them when I know no packages are due.
The process to delete them is certainly tedious enough for me, though.
Me: "Alexa, delete all my notifications"
Alexa: "Delete all your notifications, right?"
Me: "Riiiiiiiiiiiiiiiiiiiiiiiiiiiight"
Alexa: "OK. Deleted all your notifications"