It was removed probably because that the remove background tool requires the Adobe Flash Player, which got discontinued in 2021, but I'd like to see the feature bringing back. The Scratch Team does not have enough time to make a background remover in JavaScript before releasing 3.0. But support, because:
1 - People don't need to re-upload sprites and can save time.
2 - People don't need to go to external websites to remove background, and sometimes cost money. Scratch's background removal is always free.
3 - It takes a lot of time to remove background with the eraser tool.

even though i wasnt there to see it, i neeeeeeed it

I'm necroposting but I support! Nowadays I have to use erase tool in bitmap and delete the background! It's tiring. We need this!

SUPPOR TNOW