>Top row: mipmaps generated with premultiplied alpha. Bottom row: mipmaps generated without premultiplied alpha.

I couldn't see a difference in this first comparison.

Look at the fourth one on the bottom, you can see the black splotches. It's not the best example I've seen, a quick search turned up this better example, notice how the edges become all dark: https://forum.shotcut.org/uploads/default/original/2X/e/edb3...

I see thanks, the darker spots yeah. I was thinking it was a difference in the edges.

Neither can I. They look identical to me.