Canon 6D FPS override - "Low light" issue

[Alvhele]

Hello! I have Canon 6D and ML version lua_fix.2020Dec28.6D116 (recently updated from 1.1.6, still didn't fix the problem). I like to film timelapses, and for that I often use ML's FPS override feature. Generally, everything works fine until I want to shoot some dark objects in the night (e.g. distant lightnings) and I have to swich settings to the "Low light". When I do that, everything starts to be extremely noisy and has multicolored patterns all over the display, like if the sensor instantly got fried. Clearly, I tried to change ISO values, play with different FPS values, aperture, shutter and etc., but nothing helps. 
Here's the screenshoot from one of the failed timelapses: https://imgur.com/8cmCym9
I would really appreciate if some fellow photographers could help me with this unpleasant issue.

[SpasatelMalibu]

same issue with 6D, no problem with 600D.

for example, 1fps override with low light option:
1) 600D acts as expected, exposure increased, clean frames just like we make photos with 1sec exposure;
2) 6D acts like its not increasing exposure, but digitally increasing brightness, with very strong pinkish noise pattern (it's also visible in live preview). It doesn't matter if it's normal video mode or RAW video. Preview settings like Expo.Override and ExpSim also doesn't affect.

6D ML version: crop_rec_4k.2018Jul22.6D116

Really want to use low light option with 6D sensor for night videos, does anyone have a guess or solution?

[SpasatelMalibu]

Direct comparison of 600D (on the left) and 6D (on the right), same settings.

Also in the end i shake the camera and i see that frames are blurred, so it DOES increase exposure time but with this crazy noise pattern.

[names_are_hard]

Discussed on Discord.  Probably a real difference, probably due to ML in some fashion.  Independent of lens used.

Any devs with a 6D that want to investigate further?

[Levas]

Not sure, but my guess is that fps override doesn't work wel when crop_rec module is activated.
Probably it works good with crop_rec module set to off.
The crop_rec module in 6D uses fixed A&B timers for sensor readout. FPS override works by modifying A&B timers, but is overruled by crop_rec module if crop_rec module is enabled.