That's something Amazon did with Amazon sellers which is an issue.
I don't think there's been an Antitrust complaint against Twitch though -- this complaint would have to be formally raised by a competing streaming platform though, unfortunately. It is not enough that it harms creators or consumers (Consumers cannot raise the antitrust issue -- due to quirks in the US law; it is only competing companies such as Youtube, Trovo, etc, whose competition would be harmed by their actions or the US government who can have standing to raise an antitrust complaint - Antitrust violations and anticompetitive behavior harm consumers and other companies indirectly but the courts only give standing to sue to the actual competitors).
I don't think there's been an Antitrust complaint against Twitch though -- this complaint would have to be formally raised by a competing streaming platform though, unfortunately. It is not enough that it harms creators or consumers (Consumers cannot raise the antitrust issue -- due to quirks in the US law; it is only competing companies such as Youtube, Trovo, etc, whose competition would be harmed by their actions or the US government who can have standing to raise an antitrust complaint - Antitrust violations and anticompetitive behavior harm consumers and other companies indirectly but the courts only give standing to sue to the actual competitors).