I just logged on to my email to find no YouTube notifications for the past 12 hours, which is very rare/unusual.
It turns out that they have discontinued the feature, with little to no notice for users: https://support.google.com/youtube/thread/63269933?hl=en
As some one who relies on these emails and reads every single one, this is terrible...
Does anyone have any ideas for an alternative? RSS hardly seems ideal and is clunky for dozens of channel subscriptions. The YouTube front page also regularly misses stuff, especially from smaller channels.