I'm not worried about some moustache-twirling plot where tech companies effectively become the illuminati. I'm only slightly worried about politicians using the threat of regulation (e.g. revoking Section 230) to leverage companies into prohibiting things they don't like, or content favorable to opponents. I don't think many politicians would do this - the risk that this manipulation gets discovered and publicized is probably too great.
What I'm most worried about is good-intentioned censorship that further divides and alienates large sections of our society. These bans play directly into the narrative that leftist tech companies are excluding and pushing out conservative voices, and it's having the opposite effect of what is intended. For instance, suppressing allegations of fraud is likely having the opposite effect: it's triggering a reaction along the lines of, "well clearly there's something afoot, otherwise why would these companies be deliberately shutting down talk of fraud?". Who here has ever held a view and was banned from a forum, or told to stop by the forum's authorities, (electronic or otherwise) for that view? Did it make you change said view, or did it make you even more entrenched and suspicious of the authority that issued the ban? That's what I'm most worried about: companies ostracizing certain groups or topics with the intention of curbing extremism, but to the effect of fostering ever greater extremism.