Board Thread:Support Requests - Designing Your Wiki/@comment-26525672-20201010143938/@comment-26525672-20201013094552

Alright, so I've mostly figured it out.

Solution .webp
The easiest solution would be just to transform .png into .webp using GIMP or whatever, as apparently thumbnailer handles them differently. The comparison is included. Here are links to the both png and webp files.

Now I can place the .webp file wherever and it will always look good.

Solution ?format=original
Another solution is to look at the links themselves and replace the parameter (starting with ?) with ?format=original

https://static.wikia.nocookie.net/alchemistnpc/images/5/5b/Alchemist.png/revision/latest/scale-to-width-down/30?cb=20190319212349

↓

https://static.wikia.nocookie.net/alchemistnpc/images/5/5b/Alchemist.png/revision/latest/scale-to-width-down/30?format=original

Now the thumbnailer won't enable the whole interpolation so the image will look as intended.

If the link doesn't have any parameters, just add it(?format=original) at the very end.

I didn't find any methods on how to modify links automatically, using templates and such, so the only way this solution can be used is via hotlinking (as Andrewds1021 put it), or in other words, linking to the file directly, without the usual  , which wouldn't be very practical.