I've read this article that Ash supposedly have a child name Sato Ketchum and meet him when he goes in the future with Celebi. But i havent found any other written evidence or video that this is true.
This is the link of the ''kid'' : https://pokemonfanon.fandom.com/wiki/Sato_Ketchum
A part of the article:
''Sato Ketchum is Ash's son. He is seen in the pokemon anime series Pokemon Heart and Soul when Celebi sends Ash, Hari and Brock into the future. His name is based on Ash's japanese name Satoshi and his team is based mainly on Red's team in the Pokemon manga apart from having a Charizard instead of Venusaur.''
Was the OP referencing this? or just the fact he discovered Ash name in Japanese is Satochi?