That is also what I thought. My subscriptions feed shows only videos, not other posts and notifications. As far as I can tell it shows all the videos. This seems like a reasonable default to me.
That is how it works to the best of my knowledge, but most users don't browse that way; they browse from the home page. Hence it's a perceived issue to a lot of creators. Not saying I agree that the answer is no recommendation engines ("algorithms"), though...
The bell controls notifications about new content, which was a change from older YouTube, where they would notify for all new videos for subscriptions on mobile. But as the userbase grew, so too did their subscription lists, so it really is a reasonable feature. So this is the "change" the YouTubers talk about.
So basically the issue, from the creator standpoint, is that Youtube gives users the ability to browse their subscriptions, or to look at a set of recommendations, and many users choose to look at the recommendations? Sounds like you have an issue with your subscribers, not with Youtube.