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 a limited number of 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. 

Simply put, Hideki Matsuyama autographed Masters flags will likely be coveted for decades to come.

Certificate of Authenticity from James Spence Authentication (JSA)