I have high 2 digits of extensions in my VS Code, and yours is the only one that wouldn't have a verified publisher. And I certainly have more than one from solo developers.
Qt organization (because you mentioned it) also has verification. It displays a different message (because I haven't installed anything from them):
> The extension Qt Core is published by Qt Group. This is the first extension you're installing from this publisher.
> Qt Group has verified ownership of qt.io.
> Visual Studio Code has no control over the behavior of third-party extensions, including how they manage your personal data. Proceed only if you trust the publisher.
EDIT: I'm sure there are other extensions that are also by unverified publishers. It was the first time I was hit with that message though.
Qt organization (because you mentioned it) also has verification. It displays a different message (because I haven't installed anything from them):
> The extension Qt Core is published by Qt Group. This is the first extension you're installing from this publisher.
> Qt Group has verified ownership of qt.io.
> Visual Studio Code has no control over the behavior of third-party extensions, including how they manage your personal data. Proceed only if you trust the publisher.
EDIT: I'm sure there are other extensions that are also by unverified publishers. It was the first time I was hit with that message though.