I experience exactly the same. But last few days are worse than ever. Ie. yesterday my eCPM was … $0.05. And what is even stranger … most of the impressions came from United States
It seems like high time for changes in my monetization stategy.
for me ecpm grow but impressions on their dashboard drop but idk why . When i checked my apps sometimes splash screen didn;t appear. maybe fillrate goes down ?
Try Appnext! they have their new video SDK which is working awesome for me (60% higher eCPM then the old version ), plus they have a promotion this in the next 1-2 months. Search in this forum or ask @jonathan