What toner brand? I tried refill the print outcome not dark look faded

Which toner powder brand do you use. And did you manage to get 10k pages from the drum while using powder refills?

From what I know, simply refilling the toner powder is not the proper way to do it.

First the toner powder is not the same across all brands and models, the particle size for example may be different.

The cartridge needs to be cleaned out because the cheap brother cartridge does not have a separate waste container and the waste is collected inside the same cartridge which is why the xl cartridges are abit iffy.
Then there are other parts like the wipers/blades which need to be cleaned so the developer and drum rollers do not degrade prematurely.