Can't scan QR code in low light

Some phones can't scan QR codes from screens in low light because the camera automatically adjusts the exposure, making the other phone's screen a white blur. I've seen this before on older phones but assumed it was a dying problem. But the problem also exists on the Honor 8A (Android 9), making it impossible to add contacts between the Honor 8A and the Ascend Y330 in low light. (The Y330's low res screen contributes to the problem; the Honor 8A can scan the Nexus 5's screen in the same lighting conditions, for example.)

We should see whether auto exposure can be disabled, and whether this helps.