Anyone can star their own repos. Getting code merged into projects the industry depends on is a different kind of signal, because someone with no stake in your career has to review it and say yes.
NestJS
I have 12 pull requests merged into nestjs/nest, the framework's main repository, approved by its creator and maintainer, Kamil Myśliwiec. A cluster of them added end-to-end tests to the official samples — gRPC, request context, MVC over Fastify — which is unglamorous work that requires knowing how the framework behaves from the inside, not just how to consume it. I'd shipped NestJS in production for years; contributing tests to its official examples was how I paid the tooling back.
sped-nfe
While porting Brazil's most-used fiscal library from PHP to Rust (the project that became fiscal-rs), I had to understand every corner of the original's behavior — and testing my understanding produced tests the original didn't have. So I sent them upstream: PR #1313, 370 tests, raising the library's coverage from 40% to 86.5%. Merged into a codebase with 2,400+ stars that processes real invoices for real companies every day.
Why tests, both times
It's not a coincidence that both contributions are test suites. Tests are the contribution a maintainer can accept with confidence, because they don't ask anyone to trust my judgment — they demonstrate the behavior and lock it in. They're also how I learn a codebase: if I can't write a test for it, I don't understand it yet.
Both links above go to the public record. That's the point.