nombelina You can edit the available sizes to a placeholder by using our Google Chrome extension. If you were to edit the placeholders responsible and remove the Leader sizing, that should do the trick. You'll only need to do this on one page, the changes will transfer over to the others.
< image.png >
As for the grey boxes around the ads being bigger, that is intentional. This was a change done to help increase ad visibility and early signs are suggesting that it is proving to be effective. We're hoping that publishers will see some revenue benefits out of this change.