https://docs.brew.sh/Acceptable-Casks#apps-that-bundle-malwa...

> Unfortunately, in the world of software there are bad actors that bundle malware with their apps. Even so, Homebrew Cask has long decided it will not be an active gatekeeper (macOS already has one) and users are expected to know about the software they are installing. This means we will not always remove casks that link to these apps, in part because there is no clear line between useful app, potentially unwanted program, and the different shades of malware—what is useful to one user may be seen as malicious by another.

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So there might be pull requests, but Brew's official stance is that they do not actively moderate casks for malware. I guess there's something built into the MacOS packaging step that help mitigate the risk, but I don't know much about it outside playing w/ app development in XCode.