After doing some tests with some image capturers, then I quote them, I have to admit that the problem seems to be associated with the "photos" program and how the png file should be encoded when it is captured.
I have tried, from the very capture utility of maxthon to capture, like a pair of them of the same style (screenshot.exe and SnapShot.exe, unique capture files, approximately between 700 kb and 955 kb).
I have also used the irfanview, xnview and picpick capturers and only the files of the latter (picpick) seem unaffected by the "blur" that occurs when viewing the images with the program "photos" of Microsoft.
Comment that any previous file looks normal with any utility i have tried (irfanview, xnvies, imagine (plug totalcmd) etc.)
I upload a gif with the same area captured with the different capturers and reproduced in the app "photos", you notice a slight blur just after you change from one image to another, it is slight but it is there.