Well that's great design! @TeamYouTube @YouTube didn't give me notifications until 4 days later than they upload for @Carl_Sagan42, @PhillyD, & @chuggaaconroy's videos. It seems that even your notification alerts to help with your messed up sub box bug/suppression is even broken.
You see, when I close my YouTube app on my phone, I open up the YouTube app on my iPad and then an inbox came which I already open the video and it did the same thing as my iPhone. Maybe it’s all because of the bug after the update.