Cannot use wired earphones with a USB-C to 3.5 mm headphone jack dongle on iPad Pro 2018

Hi,

I bought an iPad Pro 11" 2018 recently and when I try to connect my wired earphones (SkullCandy) with a USB-C to 3.5 mm headphone jack cable which came with my OnePlus 6T, it doesn't work. The music still plays from the speakers instead of the earphones.

While the dongle works perfectly fine with my OnePlus 6T.

Any specific reason why this is happening?

Is it something that Apple has done internally so that the users will need to purchase a dongle from Apple directly?