they've lost their magic. that's all there's to say about it. better they pack it up while they still have the chance.
everything till phase 3, they worked it from the confines of common sense, still fiction but had a consistency no matter if it's iron man, spiderman or ant-man or dr strange or thor; the science and magic were all woven from the same cloth.
and now, as consistent with the rest of phase 4, they have completely given up on that constraint that stretched across everything that kept it beautiful, in the name of giving artists more room to work their magic; and the result was just the opposite, with no constraints to speak of, other than the ones that pop up for the convenience of the script, they have broken the realism in the MCU (that hadn't broken previously even with the introduction of magic and unrealistic physics of Antman).
the gap junction and the powers of dark hold and scarlet witch and America Chavez, all just thrown in without giving any of the constraints that made MCU standout. just a shake made of some characters and stories taken directly from the comics.