There could be several causes for the low eCPM (effective cost per thousand impressions). Here are some probable ones:
Advertisers may not find your ad format to be unattractive. Interstitial ads, for instance, have higher eCPMs than other ad types (such as banner ad).
Your ad targeting might not be working. In order to reach their chosen demographic, advertisers are willing to pay extra for highly targeted advertising.
Your app's ad slots might experience intense competition, which would impact eCPMs.
If your app isn't exciting enough, users might spend less time interacting with the ads, which would impact eCPMs.
Consumers may become irritated and tune out advertisements if you show them too frequently, which will impact engagement and eCPMs.
Marketers could be less likely to pay a premium for such ad slots if the advertisements displayed in your app are of poor quality or unrelated to the interests of your customers.
Marketers could be less likely to pay a premium for such ad slots if the advertisements displayed in your app are of poor quality or unrelated to the interests of your customers.
Moreover, ECPMs might alter in reaction to seasonal patterns, such as vacations or significant occasions.