My game FPS keeps dropping.

I play Valorant in my laptop. Earlier it was playing smooth with medium settings FPS was upto 120 but now I don't know my fps doenst even go up to 40fps. I don't know what is happening. Internet in fine. Resolution is minimum. Can't understand whats wrong, is it because of heating of laptop or some software issue? This issue seems to occur only while playing valorant. Help!