IPhone 12 Bottom Microphone Making Noise Because of Dust?

Recently when I use my IPhone 12 to voice call with my friends and they always hear noise coming from my side.

To figure out the problem, I use the app Voice Memo and even WhatsApp voice message, I can hear a lot of noise even when my surrounding is quiet.

I tried to blow my bottom speaker with the air from my mouth, it works, the noise was gone.

Unfortunately the problem occur again next day, the same method works but it’s keep happening daily.

What should I do?