Subs have dwindled to nothing

[velocity]

Check your analytics to see where viewers are leaving, and a few seconds before that, have a subscribe button showing up on video, with a sound effect, so that people notice it.
Voice your concern and your appreciation for subscribers. Your view to subscriber ratio is amazing.

Across all my videos user engagement isn't that bad, average view time is 2 minutes.

I think I will definitely have to make some kind of prompt in my future videos for subs.