I've never seen horizontal artifacts like that from my qhy9. I've seen a vertical bloom line but only when focusing on a bright star in a sub frame and I've seen black lines running left to right from bright stars due to clamping issues but I'm running the latest drivers which has the clamping option and using maxim to capture.
I also checked LRGB subs from an old image that had RGB binned x2. Measuring a corner sample star, definitely not the brightest star, 600sec L binned x1 = 3288, 300sec RGB binned x 2 = 8407 when totaled. If x2 binning doubled sensitivity I'd expect that RGB total to be close to the L value but it seems closer to triple? I stopped binning the camera when imaging unless I have to.
The ascom drivers allow you to set gain for each binning mode. I run X1 at a gain of 5 but all binning modes are at gain zero. Perhaps driving the camera directly from nebulosity into the old drivers carries the gain setting through to all binning modes?
I been using this one for 2 years now, a change would be nice
