It's not clear to me what the role of Congress should be, perhaps the appropriation of funding to explore/build technologies and legal structures that are more distributed and less subject to concentrations of power.
Paul Frazee's 2018 JSConf EU talk on "Formalizing User Rights on the Web" makes an important observation: technology doesn't just interact with civics, it actually drives civics; it defines what the civic structure of a community is going to be (https://www.youtube.com/watch?v=x-ffpAkviM0&t=920).
I think the proper "role" of congress is to send a message to silicon valley: fix the mess you've created, or we're going to fix it for you.
That there's a serious problem has been obvious for quite some time now, and Silicon Valley has hardly even tried to do anything about it. More likely, they've tended to tune their algorithms to best profit from it.
I'm a small government guy, but if they continue with this disingenuous "we had no idea!" song and dance for much longer, I'd fully support bringing a very big hammer down on the bigger players.
Is there something Congress should be doing? Perhaps it's not the thing for them to be involved in.