The Subscriptions feed error message is resolved for almost everyone. If you're still seeing it, know that it will be fixed soon – thanks for your continued patience! You can follow along here for any additional updates: https://yt.be/help/CBxM https://twitter.com/TeamYouTube/status/1119013035580878848 …
As long as you meet the eligibility and program thresholds, you can expect to hear back in a month or so. Note: all applications are still manually reviewed, so it does take a bit of time! If it's taking longer that likely means your channel is being held for a second review.