Thank you all for the additional insights. We will keep you posted. This is certainly a unit that have been limiting and that we might be limiting even more based on the feedback.

In the meantime, we have improved the creative/image for the PSA Ad by shortening its load time. The new image file is 20% smaller than before (now 60.8k) and the Ad Trafficking Tool that we are using (DFP) reports that the load delay will change from 500 milliseconds to 100 milliseconds. It's hard to say whether this is anything noticeable, but we hope this helps for now.

It's confirmed that the interstitial should not be running on Mobile.

Thanks again.