This is nonsense. For some people, Maths and FM are the easiest A-levels available...because they have a strong background and interest in Maths. Equally Physics is considerably easier for some.
More generally, you can't generalise which A-level is easier than another, because it entirely depends on individual preparation and motivation. If you are interested in and motivated to do Physics, and want to continue in a route which uses it (e.g. Physics, Engineering, etc) then you will likely find Physics "easier" than Economics if you have no specific interest in Economics (and vice versa, although there are no degree programmes which explicitly require A-level Economics to my knowledge).
Additionally, if you dislike writing essays and struggle generally to lay out long form prose arguments, then you will probably not do that well with Economics. Equally if you don't like performing lab experiments and writing them up and solving mathematical problems, you will probably dislike Physics. Finally in terms of "learning style" Economics is slightly more content focused while Physics is more process-oriented; in Physics you learn a toolbox of methods to solve problems, and how and when to use each. In Economics you learn information, and how to present that in a convincing and coherent way in an essay. While there is some overlap (there are some generalisable concepts in Economics you'll learn to apply to "problems"
this is a fairly core difference between the two.
You should be choosing your options based on
your strengths and interests, not what other people found. I picked Biology (in IB that is) because I had to choose between it and Physics, and one of the year 13 IB students told me "Physics is harder than Biology, choose Biology). I ended up loathing Biology, dropping it to SL towards the end of year 12, and later ended up on an Engineering degree where I did all the same Physics I would've in IB, and more, with no issues. Even then if I had dismissed what the other person had told me and spent a little time thinking about what I was good at, if not necessarily my interests, Physics would've been the obvious choice for me. Thus, as above, you need to figure out what
you are good at and then make the decision based on that.