Not replaceable with free media because (WP:NFCC#1)
The software or website from which the screenshot is taken is copyrighted and not released under a free license, so creation of a free image is not possible.
The use of a low resolution screenshot from software or a website will not impact the commercial viability of the software or site.
Fair useFair use of copyrighted material in the context of Dota Underlords//en.wikipedia.org/wiki/File:Dota_Underlords_Screenshot.webptrue
Licensing
This image is a screenshot or other image taken from a video game, and its copyright is most likely held by the game's publisher or developer. It is believed that the use of low-resolution screenshots
to visually identify the game (or other game-related article subject; for example, a character) in question