If your application is delayed, it’s usually for 1 of 2 reasons: you may not have enough public watch hours (Creator Studio shows public & private combined), or our team couldn’t come to a clear decision & we need multiple reviews. More info: https://yt.be/help/YPP-review
We can't share more specifics as that could also benefit those not playing by the rules but majority of eligible channels hear back in less than 30 days. Applications are still manually reviewed, so it does take a bit of time. Here’s a bit more info: https://yt.be/help/YPP-review