This situation may occur occasionally, particularly when a video ad faces loading issues or if the internet connection is weak.
If you cannot find the "X" button to close the ad, try swiping the ad up to remove it.
However, if you still encounter difficulties in closing a particular ad (with no "X" visible and swiping up doesn't work), please submit a support ticket and provide us with as much information as possible. We will promptly assist you with resolving the issue. :)