The slight blur you are noticing stems from the scaling algorithm wordpress uses to create the scaled down versions of the original image. When you are uploading an image, WP creates different size variations that are then displayed based on the browser resolution.
In this case the original image was 4096x2060px and sharp. Since WP uses bilinear scaling as supposed to something like lanczos to generate the smaller sizes they are sometimes blurred (and depending on prior compression even larger in filesize than the original).
Long story short: It's Worpresses fault and its a mess.
you could author Individual images for each sub-size in eg. Photoshop and upload via FTP to your server, but this is pretty elaborate.
Alternatively you could tick the box to never display scaled down versions in the image/media section in the laytheme options, but then always the original image is being displayed which might be quite large/ slow to load.
If you are on windows you could use XL converter to use the pretty new and awesome jpegli encoder to compress images with much less artifacts as usual, with that i recompressed your image from 2.4mb to 580kb with quite ok quality. This could be a reasonable compromise between quality and page speed.