It really depends. For example, it might mean that you do not know the way to do the same thing, but in a safe manner. It might mean that you could refactor your code to do things more safely.

Of course, reasonable people may also believe that it is easier to use an unsafe language directly rather than change the ways that you code.

In my experience doing embedded, operating systems work, compiler work, and others, you never need a large amount of unsafe code. 1%/4% is really about it.