iPhone 13 Pro Max Camera Exposure Issues - Not taking the picture with set exposure!

This is pretty specific but there is a reason for it. I use a white backdrop to take photos of items I sell on ebay. I have been using an iPhone for years doing this. What I do is turn the exposure up before taking the picture, and it makes the background a bright, seamless, smooth picture and does not distort the item I am picturing. I have gone through EVERY possible setting with the iPhone 13 pro max and cannot get it to cooperate. In the past, the HDR option has caused this to happen which you can turn off. That option is missing now in the camera settings app. Anyone have a thought or fix for this. Also, I worked for apple for 6 years so I am well versed in how to deep dive and check mostly all possible settings/options but I cannot figure this out. Seems like the software/hardware combo do not like when you turn up exposure that much. See attached pictures for reference.