You may need to adjust the sizing available to those ads on mobile.
You can use the chrome extension on a desktop and emulate a mobile browser via right click + inspect --- at the top corner of the developer tools there's a small device button where you can select a mobile device to show, then refresh the page. You can then activate the chrome extension to look at the placeholders for the page and adjust sizing criteria there.
Alternatively, you can setup exclusion rules by CSS if the area of the page they're populating to is unwanted - that's via the ad restrictions app within the Dashboard.
We're also encourage you to log out / clear cache and cookies / log back into the Dashboard to make sure you're seeing the updated version of the categories.