This seems to be due to not having kimageformats and qtimageformats in the inputs at build time according to some people I spoke with. I have not tested adding them and rebuilding as I'm not sure how to do that. Hopefully someone else can test this and fix the package if that works. If you look at the nix package for comparison, it has qtimageformats in the recipe.
- bug#62742: nheko cannot display certain image types (.avif, .... bdju
