If you have been puzzled about how I solved this puzzle, read this article.
It seems that some people have found it difficult to get to the starting point to apply the XY-Wing technique as shown in the graphic. Here is one way to arrive at the starting point.
Now we have arrived at the starting point to apply the XY-Wing technique as explained in my article “Sudoku XY-Wing Solves Difficult Sudoku Puzzles”.
From this point onward, you can follow the remaining steps discussed in the article.