Hmm, seenms like there is some additional compression by the forum? Seems like it reduces the size of images (and which would explain whyyou can read them just fine, smaller datamatrix codes are read just fine!)
This is the quality Im looking at;
The bigger image, perfect 90 has a resolution of 1080x1080, and perfect80 has a resolution of 960x960. Indeed, this difference is minimal.
Small image reads just fine;
bigger image does not 
Added a .zip to overcome the limitations of the forum. After several attempts, I found out that the forum simply reduces any image to below 500x500.
barcode temp.zip (4.6 KB)