Depends on the domain you’re going to work in. Nobody understands all major CS domains in depth - you typically specialize and dive deep in the relevant area. It’s like any other field: no physicist knows all major areas of physics, no mathematician knows all major areas of math. Perhaps 50 years ago when the field was really new it was possible to understand all of CS, but it’s a big field now that covers a really diverse set of topics that each are relatively deep.

Even then, you often don’t need to dive deep into the math unless you’re a working researcher for the most part. I work in languages research, and to be honest, for most of the work you don’t need to dive deep into type theory or category theory (regardless of what some internet people would lead you to believe). You generally only need to dig deep into those if you find yourself working in foundations topics where they play a strong role.