This is the question mark BG from SMAS SMB3, commonly used in bonus rooms. Giving credit is optional.
bonus, needs remoderation
Good update, for the most part.
The only reason for rejection is the small pink corners on the green blocks. I know this was present in the original, but I think that this is a great opportunity to fix it. There should be at least another spot in the palette to use.
Also, while not a reason for rejection, I did find the organization of the previous version's map16 to be better, as it represents clearly the shape of the repeating pattern. For reference (new on top, old on bottom):