Physics/Math is useful but your particular field/speciality in CS is relevant as well. I would bet a bit more money on a CS grad to understand convexity, comp geometry and optimization than a physics grad, and math majors don't always have the code skills to develop things for production.

Point of argument here being frequently neither do CS Phds and at tech companies you pair Math/CS Phds with 'production' engineers.

Also certificates aren't really rigorous necessarily and also are quite easy to one-off versus relevant programs/theses/research experience.

production is an overloaded term depending where you go