Short of some January-6th style insurrection, I'm not entirely sure what "the left" [1] could actually "do" here. I am absolutely
not advocating for a January-6th domestic terrorism event, I think that would be a very bad idea, but I also have no idea what we could actively do.
It's easy to say "reject the news agencies", and sure that might be a good idea, but that carries the risk of "substituting bullshit with different, more dangerous bullshit". This has already been somewhat demonstrated; the conservatives spent decades undermining trust in news media and that led to the rise of assholes like Alex Jones and conspiracy theories becoming normalized by American conservatives. It's easy to say "well the left wouldn't do that", but you have no way of knowing that any better than I would.
I don't want to be cynical or hopeless, but I genuinely have no idea what I could do to help fix any of the shit going on right now.
[1] whatever that actually means, I've heard about a dozen definitions.