I saw that on my pone this morning, but I had no issues closing it.

Force close the app and relaunch to see if that helps. If it doesn't, try resetting the app.

https://support.sonos.com/en-us/article/reset-the-sonos-app

I was able to X out the ad on my iPhone but on the iPad you cannot. Tried force quitting, didn’t work either. I uninstalled the app and reinstalled it and for now the ad is gone. 

• Look for a Close Button: Many ads have a small "X" or "Close" button somewhere on the ad itself. Look for it in the corners or along the edges of the ad.

• Swipe Gesture: Some ads allow you to swipe them away. Try swiping left, right, up, or down on the ad to see if it dismisses.

• Exit Full-Screen Mode: If the ad has taken over the whole screen, look for an option to exit full-screen mode. This might be a button or gesture specific to the app you're using.

• Restart the App: If none of the above methods work, try force-closing the app and reopening it. To force-close an app on an iPad, swipe up from the bottom of the screen and hold your finger in the middle of the screen until you see the app cards. Then, swipe up on the app card to close it. Finally, reopen the app and see if the ad is still there.

All of those options Saoud were attempted and didn’t work. Even tried changing the orientation of the iPad, splitting the screen - nothing worked. We’ve got a bug here :) 

You can block these ads if using a dns based network ad blocker like Pihole or Nextdns 

Using a DNS-based network ad blocker like Pi-hole or NextDNS can indeed help block ads at the network level, providing a more comprehensive solution across all devices connected to your network. These tools work by intercepting DNS requests and filtering out known ad-serving domains, effectively preventing ads from being loaded in your web browser and other applications. If you're tired of dealing with ads, setting up a DNS-based ad blocker could be a worthwhile solution to consider.