I would wager a guess that it’s your regular interests. YouTube sees that people who like machining, blacksmithing, etc. have a good chance of also being conservative. You probably are just part of the odd cases where you like those hobbies but aren’t conservative.
Your post raises an interesting point, though: even if YouTube didn’t intend for their algorithm to be a pipeline for radicalism, simply by encouraging engagement and viewership, their algorithm ends up becoming a radicalization pipeline anyways.