ExpressionContext can be copied and it provides a dedicated copyWith() method for that. However, QueryKnobConfiguration is a lazy variable that is not copied during ExpCtx copy. The copy may be performed when creating a separate sub-pipeline (e.g. for $lookup)

It may happen that parent- and sub-pipeline have different knob configurations because QueryKnobConfiguration is not copied during ExpCtx, but rather is lazy initiated. We should ensure we copy QueryKnobConfiguration with ExpCtx copy