However, the Orthodox claim to absolute fidelity to past tradition has been challenged by scholars who contend that the Judaism of the Middle Ages bore little resemblance to that practiced by today's Orthodox. Rather, the Orthodox community, as a counterreaction to the liberalism of the Haskalah movement, began to embrace far more stringent halachic practices than their predecessors, most notably in matters of Kashrut and Passover dietary laws, where the strictest possible interpretation becomes a religious requirement, even where the Talmud explicitly prefers a more lenient position, and even where a more lenient position was practiced by prior generations.
What has not been challenged by scholars?