Negative signals don’t seem to work on any platform. Instagram has a “don’t suggest posts like this” which does absolutely nothing. The only thing which kind of works is “Don’t recommend channel” (YT) / “Don’t suggest posts from this user” (Instagram). However, on Instagram this option only appears occasionally. In most cases I don’t get this option, so I need to click through to their profile to block them. By clicking through to their profile it sends a strong signal to Instagram that I want to see more content like the account I just blocked, so my feed starts filling up with garbage. Writing this makes me realise I need to quit, but it’s difficult.