Zig only has spatial memory safety in limited situations. For example: If you use many-pointers anywhere in your codebase, those places have no spatial memory safety. If you compile in ReleaseFast, you have no spatial memory safety at all.

in practice though you should be compiling ReleaseSafe and activating ReleaseFast only in functions where you need it (and that is the default)

Even the Zig compiler is built with ReleaseFast for the published binaries.

not sure what you think the safety parameters for compilation should be.