First time imported PNG strangely pixelated

I’ve been importing 512 x 512 PNG images for my surface appearances for a while and never had any problems in the quality however this time no matter what I try the image is way too pixelated.

The PNG:

The PNG as decal + surface appearance:


(I used white light to brighten image)

Other PNGs which are normal (still 512 x 512):


From looking at similar posts, I’ve mainly tried:
Increasing the resolution to 1024 x 1024.
Exported/Imported different formats.
Changing PNG quality.

If it helps compared to my other PNGs the size of this one is 98 KB while the average is around 200 KB.

I don’t know if its because of the super dark colours or because the edges are more rough, all I know is this is the first time my PNG has been pixelated to this degree.

Also I know Roblox compresses images a lot but its strange that this is the only time its been this bad.

FYI this is the PNG without the brightness:


Its not as obvious but its bugging me a lot as in game there will be a slight red light source above it.