As a non artist, I believe it would also be beneficial to you to gain feedback from people without these very skills. Honestly, it looks perfect, and I cant find a single flaw. Good job.
I wouldn’t really suggest it having a background at all, it should be the phoenix itself with a transparent background, as ROBLOX usually downgrades the quality by quite a bit when logos are uploaded.
So you didn’t make the logo lineart? Suppose it’s better that you made the render at least. Nice work there, but make sure you have the right usage rights for the original image. The website below lists it as “personal use only”.
I mean the logo and his logo look completely differing they made there’s like a low poly type and his is more like 3D render type maybe the shape is the same but it still looks completely different and it doesn’t matter if he didn’t make it or not it’s not trademarked so…