Regarding social networks and politics, I had an interesting experience with Quora, a social network that collates questions and answers from users.
Initially Quora showed me several anti-Trump responses, even though I had never written or asked anything about US politics. I was wondering where the pro-Trump stuff was . If the election was so close, I reckoned there would be at least a few Trumpistas around.
One day, someone asked something like “Why are most Quorans anti-Trump?” Many people replied to that saying they had seen mostly pro-Trump content.
I concluded that this bias is indeed baked into the system. I believe this is probably inadvertent, though, because the recommendation algorithms can’t really understand the content, but only classify it according to specific figures of merit.