P: Poor photo in the library and develop module - smart previews

I have done this for the test

It's no matter if 'Use GPU for display' is activated or not. Both had the same result. And the problem occurs in 'filled' mode also.

After unchecking 'Use GPU for display' you need to close and reopen LrC for the change to take affect.

So it appears this is a Windows 10 issue when 'Use GPU for display' is checked 

But I asked the OP here to adjust the GPU and he reported no difference. And we don't yet know his OS.

And where did this change in interpolation algorithm you report come from?

It's no matter if 'Use GPU for display' is activated or not. Both had the same result. And the problem occurs in 'filled' mode also.

OS: Windows 10 (latest)

GPU: NVidia Geforce GTX 1060

We might get to the bottom of why you and some others see this, but not without proper feedback and data. 

Andrew at the post where I reported this issue John Ellis mentioned he could not see the issue on his MacBook. So it appears this is a Windows 10 issue when 'Use GPU for display' is checked in LrC Preferences> Performance settings.

Had hoped this was a bug but if this was a new feature, then this ist horrible for me and my work.

I agree and suggest you add your Like, Follow, and Comments at the report.

The Library module interpolation for 1:3 and smaller Zoom previews was changed from bicubic to nearest neighbor. 

It appears Lightroom Classic 9.3 was changed and now creates its Zoom view previews using the inaccurate nearest neighbor interpolation

This is straight from Adobe engineering? 

Had hoped this was a bug but if this was a new feature, then this ist horrible for me and my work.

It isn't a feature and again, I cannot replicate this behavior. But yeah, if you want to believe it's a feature and everyone sees the same behavior you report, fine. Fact is, I can't and don't see it. It was never reported or discussed during pre-release so I'm not alone either. 

We might get to the bottom of why you and some others see this, but not without proper feedback and data. Your call. 

Ok, thanks. Had hoped this was a bug but if this was a new feature, then this ist horrible for me and my work.

I reported this at the below link and it was discussed at length. The Library module interpolation for 1:3 and smaller Zoom previews was changed from bicubic to nearest neighbor. 

None the less, no, I can't produce this egregious difference in the two modules, after adding noise. I'm not alone. Yes, some are having issues. Is the goal here to rant or find what's going on and get it fixed IF it's solely an Adobe issue?

Here's Library vs. Develop on an image with grain; they are darn close and this is a 33% zoom:

This is the cause of the artifacts the OP is seeing in LrC 10.0

Then why isn't it seen above? 

IF the OP wants help, he now knows what kind of data to provide. If. 

I reported this at the below link and it was discussed at length. The Library module interpolation for 1:3 and smaller Zoom previews was changed from bicubic to nearest neighbor. This is the cause of the artifacts the OP is seeing in LrC 10.0, but not in older versions. The Develop module uses bilinear interpolation, which produces a more accurate preview. 

https://feedback.photoshop.com/conversations/lightroom-classic/library-preview-zoom-interpolation-changed/5f5f462c4b561a3d4277ef23