Can you please share your Admob interstitials impressions click through? ( CTR) ?
I see a big jump lately on CTR on interstitials which is about 12% which looks very high to me, anyone seeing same results lately?
I made a thread about that same “issue” but nobody answered it 
Yesterday : overall 18% CTR / 16 euros eCPM (33% in the US, 35 euros eCPM!).
The same implementation of AdMob intersticials back in September was yielding me something like 5% CTR. I don’t know what could explain those numbers, the ads seem to pop normally when I test my app. The CTR varies a lot depending of the country, my second best country is France and I have “only” 10% there, not sure what is going on in the US
In december, max daily CTR 3.21%
How large are your impressions volume? At low impressions, CTR can be high. It’s matter of statistics - one day you can have 10%, second day 0%. It gets more predictable / averaged with higher impression volume.
Mine are still under 2%
Could be that your geo are having extra sales of android devices due to Xmas and resulting in extra downloads accedential clicking?