I don’t know if this has been posted but here is a blowup of the watermark with explanation!
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Is it true that every copier leave a notation of wht copier made the copy?
I believe it is true about the printers, not sure about copiers.
FWIW, Larry Schweikert does NOT believe the watermark theory:
https://twitter.com/larryschweikart/status/1324516282197176320?s=21
...but hes been wrong before...
IMO, it the whole thing appears to be a big nothing burger