At Protocol Buffer Compiler Installation (content/installation.md), in the "Install Using a Package Manager" section, it contains a warning about using a package manager and ensuring that the compiler version is 3+, but I'm thinking that the 3+ check predates the switch to major-less versioning for protoc?
For example, for macOS, the instructions say:
brew install protobuf
protoc --version # Ensure compiler version is 3+
And when I run that on macOS, I get 29.3:
$ /opt/homebrew/bin/protoc --version
libprotoc 29.3
29.3 is obviously >= 3, but this is the major-less version, so I'm think it's not what the installation document intends to say.