Night Mode ProRAW Files Corrupting?

I have recently upgraded from an iPhone XS Max to a 13 Pro Max, and I am very impressed with the camera quality. I always thought the XS Max took stunning photos, but this is next level!

I am facing a frustrating issue, specifically concerning ProRAW photos captured using Night Mode. I have noticed this since the iOS 15.1 update was installed a few days ago, but I cannot be 100% sure that this is when it started. This issue is affecting photos captured before and after the update, but doesn’t seem to affect those which have been captured very recently. It also does not affect standard Night Mode images, or ProRAW images captured in high light.

When I take a ProRAW photo using Night Mode, everything seems fine at first; the image looks perfect, as expected, and can be zoomed in and out with no issues when viewing in Photos. I first noticed that the issue occurs whenever I press “Edit”, at which point the edit tools will appear as expected, but the image fades from the perfect preview into what appears to be a single frame of the composite capture, which renders as a dark, very noisy and high contrast mess, which cannot be made good by any of the editing tools. If I press cancel, the image reverts (snaps without fading) to its previous appearance, but if I make any changes, save, then revert, the image remains ruined, and apparently cannot be reverted.

If I AirDrop the image to my iPad (12.9” M1 Pro, iOS 14.6), or send the image using iMessage, the sent image appears with the same quality issues as when it was being edited, however if I send via Snapchat in chat, the image is sent correctly.

Using AirDrop, if I select the option to include “All Photos Data”, the image will AirDrop cleanly to the iPad, but will have the same problems when editing on / sending from the iPad as it did with the iPhone. The only difference is that the image renders blindingly bright on the iPad, rather than the dark image from the iPhone.

If I try to open the images in other apps like Lightroom, the results are even worse, and changing the applied profile, etc. doesn’t help.

The only exceptions to this issue seem to be images which were edited shortly after being captured. These images seem to remain editable and send correctly indefinitely.

I am an advanced level (non-professional) photographer, and I use my iPhone as a camera more often than I use it as a phone. Somewhat sadly, I use it far more often than my ageing high-end SLR. I am constantly capturing and editing photos, often at night, and I like to capture in the highest possible quality available. However, I am now worrying that my new iPhone is corrupting my most important data, or at least doing something it shouldn’t be doing to my existing photos. I can only hope that this is a software / encoding bug and not a file corruption one.

I would be very grateful if someone could shed any light on this issue, and I would be interested to know if anyone else is experiencing the same issues. Thanks in advance.