I work on an open-source project for Microsoft, and I review and merge community PRs all the time. Nobody pays for the product I work on (or for C# or TypeScript, for that matter).

The Contributor License Agreement used on all MSFT open source projects doesn't ask you to transfer your copyright, though it does require submitters to agree to grant a permissive copyright and patent license. IANAL, but the copyright and patent clauses in Microsoft's CLA[0] do not look substantially different from the equivalent clauses in the Apache 2.0 license[1].

[0]: https://opensource.microsoft.com/pdf/microsoft-contribution-...

[1]: https://github.com/rust-lang/rust/blob/master/LICENSE-APACHE...