The fatal flaw mistake that you're making is interacting with it. By going don't recommend this channel or disliking you are still interacting with it. Interacting is a positive metric. Ignore with your brain and don't interact.

damned if you do damned if you dont haha

Not true in my case. Also, removing content pieces from watch history helps immediately.

My usual routine is: dislike, not interested (or don’t recommend channel in case it’s all bad), then go to history and X the video. This clearly works for me.

To remove shorts completely, use Unhook ext.