Why does YouTube recommend right wing content to my mum?

My mother is not very politically literate but became interested in politics after covid. She’s very socially progressive, likes gay and trans people, not racist, etc. but is exclusively recommended right wing political videos on YouTube. She’ll has no idea who these people are but ends up watching some of their content because that’s all that’s on her YouTube. It’s always American or British far right, we’re from New Zealand, so it doesn’t apply. Does YouTube have a political bias? Or is it simpler than that?