The "AE" and "AF" stood for Zen and Zen+ - not "original" and "new". They were present in all desktop CPUs of those generations. (2000G and 3000G series APUs were "FB" and "FH", though.)
E.g. (Boxed versions):
Ryzen 7 1800X: YD180XBCAEWOF
TR 1950X: YD195XA8AEWOF
R7 2700X: YD270XBGAFBOX
A Ryzen 5 3600 with an "AF" would logically be a Zen+ chip - a 2600 in disguise - in a reversal of the 1600 "AF" situation.
Also, the cache amount doesn't match either the 3600 or the 5600: 36 MB would require a 8-core CPU: 32 MB L3 cache + 0.5 MB L2 cache per core.
I'd wager this is either a bogus entry used as a placeholder for the storefront development and testing, or the store is trying to swindle customers. If they let people imagine they're getting a good deal without lying, they can get a better price, or at least get the unsold products moving; Having this now meaningless nomenclature - but one that has a good reputation among enthusiasts - must mean it's a 5000 series in disguise, right?