I’ve noticed this change in quality as well.
There are chroma shifts, for example in images with deserts, where the shadows have a blue tint. I also observed that in a series of images, sometimes one appears that looks like it’s from a different model, it has a slightly different style, and the typical new errors are not present. Additionally, errors have mainly appeared in bright spots, such as white spots in the eyes or strange reflections on reflective surfaces. Also, in dark scenes, suddenly volumetric lights have appeared, making it nearly impossible to achieve a dark background without using prompt tricks with side effects.
There was a model update that didn’t improve the model but instead reduced the quality.
But the clearest indication is what I call the ‘bird-shitt-moon.’ This ugly moon with the very dark spots is the most clear indicator that there are 2 differed models in use, or when the update happen.
Here’s another post that describes the same problem. It seemed like there were two versions of weighting data in circulation, and it appears that the older model contains fewer errors.
And i speculate, there was a Nightshade infection, maybe some effects are a holdover of this.