I would say calculations hard given the exams have been quite clearly moving in that direction
Imo theory hard is harder through since most phys maths is pretty simple, whereas theory hard is usually just big mark questions where a super thorough explanation is required which are a lot easier to lose one or two marks on. At least in my class who mostly don’t try at all, most people can do the calculations whereas barely anyone can keep up with all the content knowledge required for those long responses