Have I ever found a need in real life for solving second order linear nonhomogeneous differential equations? No, but then I'm not in a job that relies upon that.

But a solid understanding of maths (I did an OU maths degree between 2005 and 2012) has definitely helped me in various aspects of my job (software development). General calculus, set theory, logic, minor bits of geometry, trigonometry, Newton-Raphson, limits of series, etc have all had their uses.

There are chunks of machine learning that are heavy on the maths theory. Not being phased at all by greek symbol filled linear regression equations is definitely useful.

But the biggest part that was useful was Number Theory and how it is fundamental to asymmetric cryptography. That's helped me enormously as some bits of cryptography just seem "obvious" when you understand the theory behind it.