That is CGA.
I had CGA 66 and 67 that PMG regraded and they came back 58s. Others came back 2 to 3 points lower, but yours beats them all.
If you are buying CGA graded notes you have to treat them as raw and pay for them as such. For US currency, I only trust PMG and PCGS, but I prefer the PMG holders.
Give PMG a call ask them what was wrong with the note, sometimes they keep notes about the grading, and let us know. The note looks like it might have a faint tilted horizontal fold above the word FIVE.