This highly three-dimensional square comes from “100 Bright and Colourful Granny Squares to Mix and Match” by Leonie Morgan on page 102 and requires a skill level of advanced.
I would agree with this rating because when constructing the petals in round 2 the instructions are not immediately clear. When it says to “turn, ch 3, then tr in the same stitch”, you actually need to place the treble in the top of the previous one and so construct a row directly above the 4 tr just stitched. After placing 4 tr atop these previous 4 followed by 4 ch, it again says to turn, this returns the stitches to the chain space of Round 1 in order to create the next petal. If you follow the instructions carefully and are prepared to pull out and redo a few times, a less experienced crocheter could finally master it. It is worth the effort.
Please note that there is a printing error in Round 3 when it says to end colour C. This is a printing error because colour C continues in round 4.
I have already crocheted this square in my previous colour scheme and you can see it here.