What causes bright banding in CMOS sensor?

This is caused by saturation of the sensor. If the pixel well is overloaded, electrons leak in to neighboring pixels which causes the streak. A nice article that has a more in depth explanation.

That is a readout issue that can occur with CMOS sensors.

It is essentially the same thing as CCD "smear;" only in a horizontal direction rather than vertical, and CCD sensors are much more prone to it due to the difference in readout technologies.

It will only occur with a very high contrast source against a very dark BG, and usually only visible with exposure recover/pushing.