There’s nothing ‘fair’ about it because Facebook/Insta/Tik Tok isn’t aggressively pushing right wing content the way Musk’s Twitter does, the For You tab is literally chocked full of MAGA contents actively filling your feed. Also I’m not sure what you meant about Google because the only big social space they own is YouTube and YouTube is 100% not lefty friendly in its content moderation, you can’t possibly claim that when anything from Ben Shapiro to alt right incels to Andrew Tate to fake natty bodybuilders and every other color of kooky right wing characters have thrived on that platform over the years, and then on the other hand a show that’s not even especially left wing like David Pakman has ran into multiple rounds of demonetisation and contents flags.
Social media space by its nature skew left because of the demographics populating it. Having more lefties because they are young and grew up being used to airing their politics online is not by itself proof of the network being biased, it’s just how it has dynamically evolved. What we are seeing is a concerted effort from the right to invade those space and artificially suppress any ideology that doesn’t agree with theirs, backed by big money in an unprecedented way, and it’s succeeding because there’s no equal pushback from the left, and the result is a lot of young impressionable boys being redpilled and start parroting the ‘sigma’, ‘alpha’ mindset before graduating to hating wokes and women. We are watching a gender divide growing in politics that has never been seen before due to that culture war shit the right has been waging, not limited to, but predominantly on these online spaces.
It's also outright wrong to claim that pre-Musk Twitter was "very left". That might be what the culture felt like to him, perhaps based on the curated content people posted here, but studies showed that the algorithm consistently pushed right-wing content far more aggressively than left-wing content.
The same broadly applies to Facebook, and YouTube, as you say. They've contributed to the resurgence of far right conspiracy nonsense as much as any other platform. It's meaningless to somehow claim those for the left.