Another Many-to-many example within this usecase would be “subscriptions”. Users can subscribe to multiple channels and channels can have multiple users subscribed to them. You would use another relational table that stores the channel_id & user_id, with uniqueness for both together, since “being subscribed to one specific channel multiple times” doesn’t make sense and perhaps put a column to store “hitting the bell” in there too.
It’s been a while since I’ve watched it myself, but remember them going into the ownership structure.
https://www.youtube.com/watch?v=hNZy603as5w
There’s basically no way for them to not make it a subscription model.