Specular input, principled shader in 4.0

Yes there has been some changes. Some main ones are given here (more or less, there is no one to one comparison):

(the Specular Tint used to be an amount, taken from the Base Color and is now it's own Color, so that arrow, among others, is not very precise.)

That said, it might be better to stick to the Blender Versions used in the Courses.

100% recommend sticking to the Blender version used on each course. Blender may get updated a lot but the core knowledge rarely varies, that you can manage with any Blender version and you avoid a lot of pain when it comes to following on screen.