So, they didn't detect anything until the drones were almost there and scrambled to respond with the only thing around - a shiny new Su-57 being kept safely away from combat?
TBH these kinds of small, relatively slow moving and low flying targets are a terrible match for jet fighters so it's not a surprise they didn't stop most of the drones. I think we'd see other modern fighters struggle against them, too, especially without radar support from the AA batteries they're using to protect Moscow, Kerch, and Valdai.