俱舍論記 22.81

22.81

「謂諸樂受至故成顛倒」者，此釋初章。謂諸樂受依自相門雖性是樂非是苦苦，若依異門亦有壞苦及行苦性。世唯觀樂，不觀為苦，故成顛倒。

As for "That is, pleasant feelings... therefore it becomes an inversion": this explains the first section. That is, although pleasant feelings by way of their intrinsic characteristic are pleasurable by nature and are not the suffering of suffering, by another way of explanation they also have the nature of the suffering of deterioration and the suffering of conditioned existence. Worldly beings solely view them as pleasure and do not view them as suffering; therefore it becomes an inversion.