I noticed this a few days ago but didn't realize the scale of the issue until I played around with the Exposure values and tested them to the limit.
I've attached two screenshots of the Develop module. The control image is an RAF photo with Exposure boosted to +5. The experiment is a DNG derived from the RAF, with a Denoise amount of 30. The effect manifests at all amounts from 1 to 100. However, the banding is not present in the Enhance Preview window. I have also attached the original Fujifilm RAF from my X-H2s camera (lossless compressed) and an affected DNG with Denoise.
I can't detect this phenomenon in NR conversions before LrC 13.3.
The significance should be self-evident. The banding artifacts appear in images with lifted shadows or underexposed photos with boosted brightness.
Lightroom Classic version: 13.3.1 [ 202405311538-6d7c0308 ]
License: Creative Cloud
Language setting: en-CA
Operating system: Mac OS 14
Version: 14.5.0 [23F79]
Application architecture: arm64
Logical processor count: 12
Processor speed: NA
SqLite Version: 3.36.0
Power Source: Plugged In, 80%
Built-in memory: 32,768.0 MB
Dedicated GPU memory used by Lightroom: 5,764.7MB / 21,845.3MB (26%)
Real memory available to Lightroom: 32,768.0 MB
Real memory used by Lightroom: 3,716.8 MB (11.3%)
Virtual memory used by Lightroom: 424,322.1 MB
Memory cache size: 1,238.0MB
Internal Camera Raw version: 16.3.1 [ 1889 ]
Maximum thread count used by Camera Raw: 5
Camera Raw SIMD optimization: SSE2
Camera Raw virtual memory: 2281MB / 16383MB (13%)
Camera Raw real memory: 2285MB / 32768MB (6%)