To me, I think Gustav Mahler is overrated. The first Mahler symphony I listened to was the 1st symphony, I was indifferent towards his works but when I listened to the No. 7, I didn't enjoy it. I listened to other symphonies by Mahler and I liked it but I still don't understand why Mahler is hyped so much.
It took me time to enjoy some of his symphonies. Haydn who has much more symphonies that I like is not hype like Mahler. Tchaikovsky is also not as hyped as Mahler but almost everyone knowns a tune by Tchaikovsky.
I do appreciate his effort and all his works and I do not underate him in any way but personally, I think he is overrated.