Is this dust in my iphone due to manufacturing defect or is it because a dust particle is stuck in between my screen protector and screen?

Hi pratham264,

Thanks for reaching out to Apple Support Communities. Seems you have a question about dust in between your screen protector and iPhone screen, we can help answer your questions. This is not a manufacturing defect. The dust most likely happened when the screen protector was applied to the iPhone's screen. You would need to remove the screen protector and either remove the dust or apply a new screen protector.

All the best.