Yes that could be millions of report.
But, that could only point out to the same ads so that's not a matter it could be just counts but it will direct to similar and specific ads.
Reports aren't specific they only give categories while reporting so still the queue will be huge to analyse.Many popular individuals accused Youtube for promoting such things that is why Youtube is start terminating the accounts but still they need to find employees with crypto related knowledge so they can validate the report accurately.
I think you're literally thinking for each of ad report to be separated from each other.
What I'm explaining to you is one ad can appear to thousands of videos and if all of the viewers reports one ad then that's just go into category, it's not literally that they have to count it one by one.
I am also saying the same, one ad could be reported multiple times to get the priority in the checking or investigating, unfortunately most of the people don't understand what it is that so people reporting crypto related ads could be less compared to general ads and videos that is why it its taking more time.