No doubt about it. When I was at school 30 years ago, half of what is now in AS maths and AS physics was part of O Level maths and physics. I was on holiday recently and bought a second hand O level textbook. It contained over 500 pages of densely written physics more suitable for A level than GCSE.
Exams are no doubt more suited now, but to say they are the same difficulty as 25 years ago, only different is frankly, lies.