Quality of image drops when importing to Roblox

Hello. Our studio’s GFX designer (@Tsubasa_GFX) designed a credits image for our game. The quality looks great normally, but when we import it to Roblox the quality drops significantly. How can it be fixed?

What it should look like:

What it looks like:

Roblox downscales all uploaded decals to 1024x1024 images—the two available workarounds are typically either to cut it up into multiple images and line them up in studio, or to design the image with GUI’s instead