2.5k resolution is probably too low for this issue to not be a real issue especially if the monitor is fairly large. You typically need 4k for it to disappear. The typical guideline for regular vision is that for 4k you need to be 1.5x the size of the screen away for the pixels to be invisible. So for a 32" screen, you need to be 4 feet away. People typically sit closer than that o optimal display size for 4k is more like 24". For 1080p, the rule is 2x the size. So for 2.5 k about in the middle of those two. Say 1.75x. So if you sit 3 feet away, your display should be smaller than 20" for this potentially not being a problem. Even smaller for a laptop display which people typically view even closer. Anything bigger and you'll be able to see the pixels.
Indeed the only accurate display in ANY program is when viewing at 100%. Every program uses different scaling algorithms to scale the image down to display resolution. In develop for example when you are in Fit view, the algorithm subscales the raw data, renders it into linear prophotoRGB and then scales it doen to display size in that color space and sharpens slightly. However in Library in Fit view, a jpeg preview (itself typically scaled down already) which is in adobeRGB or sRGB space is scaled down in the gamma corrected space to the display resolution. This leads to potential differences between the Fit view in Develop and in Library. Again this will only be visible if your display resolution is smallish.
For the question about which is more accurate.. The most accurate for 100% is Develop. The most accurate (as defined by closest to a jpeg export) for scaled down views is surprisingly the Fit view in Library. When in a scaled view, they all are acccurate in their own way and they all are inaccurate in others. There is no one way to do this. These are consequences of how images have to be scaled and they lead to the small variations you see here. Also note, we haven't even started talking about output sharpening which radically changes this equation again! Most people never notice this and it took me a while to figure out what you were talking about. Also you should be aware that some of the differences might be psychological and based on what your brain perceives as context. For example, the background color makes an enormous difference on color perception.
That said, I took another look at your screenshots and there is adifference in there that is not explained by the scaling. The output is less warm in the skin tones and other tones where there is no major detail to cause scaling issues than the Lightroom view. This is clearly not right especially if this was in the situation where you set the display profile to sRGB. There really should be no difference in solid color areas. There is one more possible cause for issues such as this and that is GPU driver problems. Try turning off GPU acceleration in Lightroom and see if the issue persists. Also look for updated drivers. You typically have to go to the GPU maker's website to find those. Windows update doesn't automatically install them.
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