What is leftist about it?
The majority of the season are (Season 11 to 13 not so much). The new season is amazing tho.
Its not ultra leftist, its just better than most piece of medias. The leftism Doctor who is in the detail. In fact sometimes you might not even notice it, but in short, they are making the right call and choices.
Doctor who is a big series about change and acceptation. It also have an anticlassist message.
But overall, its very fun, goofy and emotionnal.