I wonder what is the real functionality of this feature on the program, for example, to be using Krita as an animation program rather than drawing, this is a very annoying feature when I want to paste only a specific part of one frame to another that is already drawn.

How useful is this function when it is drawn? (Considering that at least for me it is also annoying when I'm only drawing and I'm not doing animation)

I want to know if this is something deactivable, and if so, How do I turn off this function?

And finally, if you can not turn it off, could you add a switch to activate and deactivate this?

You'll have to rephrase your question, because the way it's written, it's pretty much incomprehensible.

Do you mean the function that automaticly create a new layer when you copy/paste from a selection for example?

The purpose of this feature is to allow you to reposition or transform the pasted content before you put it onto the destination layer. Otherwise it would just paste it in the same place it was before - or just in the top left corner - and it is rarely the exact place you would want it to be. All art programs has something like that, just some of them have it very clearly stated as a new layer (Krita), some are more sneaky about it ("floating layers" or "floating selection"? in Gimp, I don't remember how it was called exactly), some probably hide it well and merge the layer for you the moment you confirm the transformation.

In animation this feature can be a bit less convenient even if it follows the same idea. Notice that the layer the content is pasted on (if you copied from animated layer) has already frames that you can reposition so merging will work just the same was as on standard layer.