It may be that those who thought it was easy may not have understood the complexity of the question, or jumped to obvious conclusions when the correct answer required a bit more insight, which those who described it as difficult may have recognised. There's a difference between did they find it difficult (personally), or did they think it was a difficult test (for everyone), which tends to be lost in these type of discussions.
Another factor to take into account is How selfcritical is the person. It seems to me that girls are generally more selfcritical than the boys.
My DD came out of the piano exam and reported me every little thing which she has done wrong and my DS came out with a broad smile saying that everything went very well. My daughter got a distinction and my son got a pass
Last year my daughter found the test to be quite difficult (maths in particular) and she got a good score and a place in GSSG.
My friend’s son who got extremely high score of 390 last year said that the test was quite hard.