I would think that providing an echo chamber for an existing belief would make somebody less inclined to consider alternative view points. Further, I would suspect social media could sway people still undecided on issues. We've already seen reports on how Facebook deliberately manipulated the feeds for certain people to encourage either positive or negative emotional responses to a subject.

Couldn't those impacts be seen as fueling division and polarization?

I kind of get it though social media boosts confidence in bias beliefs but those bias beliefs are already there people just weren't as loud about them or inclined to act on them like they are now.

You're misusing the word bias.

Could've used this one:

https://www.nature.com/articles/d41586-023-02420-z