Well it has the 6N21B tube instead of 12AX7, and early 2021 I stopped offering those and switched completely over to 12AX7. But it also has the 125B enclosure and top jacks, those weren't standard for a while. If I had to guess I would say most likely November or December 2020. There may be a serial number (date code + batch number) on the inside of the bottom plate that would tell you exactly, but if it was made before I standardized that it may not be.
EDIT: looking at the picture it's a little hard to tell but I believe it looks like it was laser engraved instead of UV printed, which would point to most likely November 2020, as I think December 2020 is when I started UV printing everything.