This may have been raised elsewhere but nothing came up in a quick search.
I have rectangular and horizontal linear artefacts of various sizes appearing after I have applied DeNoise, but it’s not consistent. I export the selected file from Lightroom (Classic 12.2) to DeNoise (3.7.0). When I am happy with the edits, the file is saved back into Lightroom. When the image file is displayed there will often be a shape appearing in the background (a square, a line, a rectangle). As I mentioned, this not happening with every picture I process through DeNoise, but when it does occur it does not appear that the picture background is the problem as this has occurred across different backgrounds. When I reprocess the photo again, then there is a high chance that the photo contains an artefact of a different shape. Some photos I’ve had to process 3-4 times before they were ‘clean’. Just one example attached below