About 2 months ago, it was a makeup channel by some Instagram influencer. There's absolutely no way I subscribed to that channel voluntarily.
Today morning, it was a channel named "(Twitter) - Tesla" (seemed like an official channel) featuring a live stream with Musk and Dorsey among others.
Such a recommendation in my feed isn't too surprising, given my tech-related interests. But this wasn't just in my feed list: This was in my list of subscriptions! And that is just impossible - I'd never subscribe to anything related to Twitter or Tesla. It's also the first time I'm seeing that channel; the name is unusual enough that I'd remember if I'd seen anything there before.
Anyone else with high subscriptions noticed such involuntary ones?
I myself think I've only experienced the opposite; mysteriously becoming unsubscribed to channels I am 100% sure I would never unsubscribe from under any circumstances.
Unsurprisingly these tend to be channels with a political bent.
Returning to my initial question, I have had a lot of channels which I've found myself wondering "when the hell did I subscribe to that?!" Only to realise it's an old creator who shifted focus.
It also wouldn't suplrprise me if sometimes channels get bought up for commercial purppses, which sounds more likely given your description of the mystery content you're seeing.
That's the Elon Musk Crypto Scam. Criminals buy spear phished YT accounts (typically with tens of thousands of subscribers), remove all the videos and then reskin it to look like an official SpaceX or Tesla channel. They're then able to run double your money style scams on it for hours on end. YT knows it's a problem but doesn't seem to care. I've reported the videos before, gone to sleep and woken up to still find it going the following morning.