Suddenly I stopped getting notifications of uploads by YouTube channels that I'm subscribed to. For 2 days I googled but results were swamped by "how do I stop email notifications", but eventually I found one individual, also based in the UK, who was querying the same problem.
Today, after searching the Google/YouTube forums, I found that they have actually stopped sending notifications because:
(1) Fewer than 0.1% of the emails are opened.
(2) Users have told them that the emails cause Inbox overload.
You don't get these emails unless you have asked for them.
But you can still get them, say YouTube, if you use the YT app on mobile or if you use Chrome browser on PC.
And that, IMO, says it all.