Indeed, the political echo chambers on Twitter are so extreme that individual users' political leanings can be predicted with high accuracy: you have the same opinions as the majority of your connections.
Similar to my previous annotation, I believe that the more you share or interact with content that shows exactly where you're politically standing, the platform will then show you more content that pretty much proves the said bias. I've seen this before on Facebook during the presidential elections in the Philippines this year. The acquaintances that I have back home and their friends pretty much share/voted for the same presidential candidate. I only go to Facebook to read/view my friends' posts but I would say that even though I never interacted with any of the content regarding the Philippine presidential election, my feed for months contained mainly memes, articles, or posts about it and they're mostly about how bad the OTHER candidate is.