Well here it is - the signed Masters flag that everybody is looking for - an actual 2021 Masters flag that is autographed by this year's Champion Hideki Matsuyama. Due to Covid-19, there were hardly any attendees at the 2021 Masters Tournament, and very few 2021 Masters Flags were sold. Several days after the Masters Tournament (after proper Japanese quarantine period), the first ever Masters Champion from Japan met the Prime Minister of Japan and gave him...an autographed 2021 Masters flag. 

But this one of ever more special, as it is also autographed by Matsuyama's caddie Shota Hayafuji, whose bow from the 18th green was one of the great golf images in history.

Certificate of Authenticity from James Spence Authentication (JSA)