I know what you're hearing on YouTube, from guys like Overlord DVD, Midnight's Edge, et cetera. They're telling you DSC (and by proxy SNW) is no longer canon. This is because of a scene in the Lower Decks finale where a Klingon B'rel BoP and its TNG-era crew transforms into their DSC-era counterparts due to the rift.
They're most likely wrong, and DSC is still canon. Lower Decks hasn't decanonized anything, especially with the SNW crossover a while back where Boimler and Mariner mat the SNW crew. Think about it. If their reasoning is that Lower Decks alternate timelines decanonize DSC, then by that logic, the episode prior to that one means that DS9, Voyager, and Enterprise are no longer canon, since we see alternates of T'Pol (ENT), Garak (DS9), and Harry Kim (VOY) are part of the Anaximander's crew, and their presence decanonizes these shows.
They're most likely wrong, and DSC is still canon. Lower Decks hasn't decanonized anything, especially with the SNW crossover a while back where Boimler and Mariner mat the SNW crew. Think about it. If their reasoning is that Lower Decks alternate timelines decanonize DSC, then by that logic, the episode prior to that one means that DS9, Voyager, and Enterprise are no longer canon, since we see alternates of T'Pol (ENT), Garak (DS9), and Harry Kim (VOY) are part of the Anaximander's crew, and their presence decanonizes these shows.