Weird creaking during braking

[max yaris]

Hello,

Im experiencing a really inexplicable creaking noise in the brake system. I apply the brakes and it sounds like an oscillating creaking/rubbing noise. Brake pads and discs are brand new and calipers we're fully inspected and cleaned of any rust on sliding surfaces. The rear is in good shape as well, shoes are well worn and springs and levers seem to function normally. I lubricated all the contact points on the backplate and the pivot points as well with silicone ceramic grease. Let me know any of your insights, I'm at a loss here.

Thanks