Improve blur appearance

[ItsPasi]

I've recently come across an issue while making my own mod. It is that computer software often blurs things the wrong way.
A great explanation can be found here: https://www.youtube.com/watch?v=LKnqECcg6Gw&t=153s

The blur of this mod has this same issue, so it should be possible to improve the appearance with a not too complicated fix.