After searching Google for the Roblox logo with a transparent background and finding none, I decided to recreate it. It was drawn pixel by pixel (rip my right hand) and the background is perfectly transparent.
That’s impressive! Now if you search up “image transparent” multiple sites will come up that will make any file have a transparent background, and you can download the transparent image. I would recommend using that in the future.
Roblox provides the default logo alongside the square one on their press-kit page. There are also brand guidelines that you’re supposed to abide by there.
It appears they also do not want creators using the red logo.