README.md contains this:

Feature vendored-openssl can be used to statically link with openssl if feature openssl is enabled.

Building portable binaries

When building with the dist-server feature, sccache will depend on OpenSSL, which can be an annoyance if you want to distribute portable binaries. It is possible to statically link against OpenSSL using the openssl/vendored feature.

Seems the top line above should be dropped, as that is a section generally about building, whereas the bottom part more appropriately is specifically about static linking.