Low quality photos in Lightroom online

kapito$hka  wrote Look to the sky. It's not normal

EDITED: Your uploaded NEF in the Web Gallery look worse than mine probably due to higher Vibrance & Saturation settings. Here are the links:

Yours: https://adobe.ly/2MZ4cy9

Mine: February 13, 2019 2 by Todd Shaner

After checking further this is also happening when exporting the NEF inside LR Classic to JPEG, 80 Quality, sRGB, 2048 Long Edge, with Standard Sharpening. Using 100 Quality sRGB or 80 Quality with Adobe RGB Color Space there are virtually no artifacts. So this isn't an issue with LR CC's Web Gallery app.

There is a large out of sRGB gamut color area in the sky, which is causing the artifacting in both the uploaded Smart Preview DNG raw file and exacerbated in the sRGB JPEG file downloaded from the Web Gallery. The below Soft Proof in LR Classic is with my settings. Using your LR Develop settings there will be larger out of gamut areas.

Here's a comparison of the NEF with my settings applied and its companion Smart Preview DNG file created in the LR Library module. This is ALL local to LR Classic Desktop app, which proves this is causing the artifacting seen in the LR CC Web Gallery app. The Smart DNG is a reduced size raw file format that should render the same as the original raw file except for its lower pixel dimensions. I'm going to investigate Smart Previews further and will report back what I find.

The only solution for now is to use LR Soft Proof mode and adjust the image so that there is less out of sRGB gamut area. Controls to use are Vibrance & Saturation (lower settings) and HSL controls (lower Saturation in the out of gamut areas using the TAT sampler.

Your comment, "Why did Adobe make such function if result is not usable???," is acknowledged.....at least by me!