I tried doing that
here, but without any response.. I can only post on their 'community' forum or whatever that is. It seems impossible to directly ask them a question, or am I missing something?
@Nikunj: (for some reason the support team is very reluctant to provide any information about this, let me try to explain what I have learned thus far.)
"But I just want to understand the error, and why I am getting this error."
If the user does not consent, all consent toggles are switched off (that is probably the way it should be, I think that you get the same behavior on web sites). The problem is that somewhere in the back-end (Funding Choices I guess) triggers the error you mention, because of some missing consent, and because of that, AdMod does not serve an ad. It's ridiculous, it doesn't make sense, but Google doesn't seem to have any internal communication, nor are they willing to inform and help their users, who keep integrating UMP and start losing money. Check also
this and
this post for more on this issue.
"Will it affect the revenue from the ads?"
Yes, it will. I integrated UMP in one of my apps and revenue started dropping after a few days. I am about to release an update where I reverted back to the legacy consent.