The page of my bank's website (ABN AMRO) which shows an account's transactions does this in the worst way. It all loads perfectly, it shows the transactions, I move to click on one or the button for a new transfer, and boom a message gets loaded in at the top which shifts every fucking item on the page down 20 pixels or so.

The message is always something inane like 'markets go brrr¹', and it's never something I need at the moment on that page (or anywhere else). I can dismiss the message (hooray?) but it always comes back the next time, so that isn't actually helpful at all.

1: Obviously they use carefully blandified corporate bank language for those messages.