Good, and then we'll get the government to start banning dark patterns.
Actually, I suspect that such a law would be on even shakier First Amendment grounds, but here's a test that might bring this regulation into the realms of competition law rather than regulating speech:
Whenever a (sufficiently large) platform makes a UI change about which the FTC receive multiple negative comments, that platform is required to run a poll of (some random subset of) its users, with a wording specified by the FTC, asking the users if they like the change or they find it manipulative.
If most users think that the change is negative, then that's a de facto / prima facie case of the platform abusing its monopoly power to the detriment of its users, since if there were a free market then those users would simply move to a competing platform.