Hello @kotorichiiya and welcome to the forum!
Because the information you gave us about your issue are insufficient to give a well funded answer, I can only guess what your issue may be.
Would you please also answer these questions in addition to the question by @sooz?
What is your operating system?
What version of Krita do you use?
From where you got your version of Krita?
There will probably be more questions, but these are the usual basic questions that need to be answered so that we can help you efficiently.
If you speak from the representation of your colors on different platforms on the internet as well as on different displays that ARE NOT COLOR-CALIBRATED, or how they are displayed in different programs, you may want to read this post from me:
If these problems, I described above, are the problems you face, you will find a lot of topics about this using the forum search, that is reachable via the magnifying glass symbol in the top right of the forum websites. Use search terms like dull colors, bad color, color issue, color problem or simply color, to find more topics than you want to read and that are all caused by the misunderstanding of color and color management.
Michelist