Some teams turn on the switch in their compiler or linter that turns warnings into errors. Not many people invoke their compilers directly anymore, so disabling this requires digging into the build system configuration, which is not always simple (and as the OP mentioned, can require a full rebuild).
Sometimes this is even baked into the language itself. For example Go can be strict about unused imports and variables. Python is strict about having correct indentation.
Sometimes this is even baked into the language itself. For example Go can be strict about unused imports and variables. Python is strict about having correct indentation.