Question Fan making noise and stops working properly

Jul 19, 2021
Hi, recently the fan at back of my desktop started making loud noise and loses RPM, it also has some yellow parts on it, I think it was purely white before.

I tried to use fans calibration in BIOS, it changes minimum duty cycle on every other fan to from 60 to 60 but on this one making noise it changes from 60 to 31 and after that it works normally.
It sounds like something is blocking it, also it slows down after it starts making sounds and RPM goes down from 1075 to 715

What can be the cause of this?

My Specs are :

Processor: AMD Ryzen 5 3600
Ram: 16GB 3600MHZ CL17
Windows 10 Home
Graphics: Sapphire Radeon RX 5700 XT PULSE 8GB GDDR6
Case: SilentiumPC Regnum RG6V EVO TG ARGB
Power Supply: Be Quiet! Straight Power 11 650W 80Plus Gold