Oh wow! That's such an odd thing to happen! It's honestly mind-boggling how certain features like indexed-color mode for PNGs can just... be taken away? Regardless, thank you so much for all the work you've put into everything!
Clip Studio Paint also has all the tools you need to create pixel art, so I do think it would be nice to have an indexed color mode too.
That said, I doubt there are many situations in modern game engines where they only accept indexed colors. Times sure have changed.
