Update 2 (2025-04-24): Rephrased addon summary for potentially more clarity about how it works, with integer scaling mentioned explicitly in particular.

Update after user reply (2025-04-24): “AI” has nothing to do with this addon, the addon doesn’t make any image look good. The addon does exactly what’s described in the very first paragraph here on the AMO site: “Prevents blurring images which have their size in physical pixels an integer number of times larger than their natural size.” If your OS-level zoom is lower than 200%, you won’t see any effect on most images in internet. Learn more about integer scaling, e.g. in my article: https://tanalin.com/en/articles/integer-scaling/
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Good-enough and working software doesn’t need updating. The addon does exactly what’s described, read the description more carefully (see the official webpage of SmartUpscale for more details). If you don’t see any result, you probably just don’t need this addon and actually need some different functionality. What are the resolution of your monitor, and OS-level zoom (e.g. 100%, 150%, 200%)?