"Illusory or flawed knowledge is based on non-fact or the non-real", laced with this deep meaning viparyayah mithyajnanam atadrupa pratistham, stands as the eighth yoga sutra of Patanjali Yoga.

Viparyayah perverse, unreal
Mithyajnanam illusory knowledge
atadrupa not in its own form
pratistham occupying, standing, seeing, beholding

Illusory or flawed knowledge is based on non-fact or the non-real.

Perverse, illusory or mistaken knowledge is induced by error or misapprehension, or by misinterpreting one thing for another. It is based on the misrepresentation of reality.

Incorrect understanding and mistaken conceptions yield wrong feelings and contaminates the consciousness. This blocks the sadhaka in his efforts to go through the seer, and may give rise to a dual or split personality.