Spencer didnt lose his leg. At the end of Episode 7, we see Spencer walking naturally to Alexandra’s grave. We are given a shot of both feet wearing the same boots. No prosthetics visible.

I truly believe the experts who write these articles (and YouTube videos) only half watch the shows or deliberately post misleading content. Elsa says there are two sons.

John Dutton Sr (James Badge Dale) live to see Jack grown. Thats the one child that lived to see his child grown. We know that Spencer lives until 1969 so his sons die before theyre grown. This leaves Jack (John Jr) and Elizabeth’s son to carry on the family name. Plus, In Season 4 of Yellowstone, John Dutton tells of the phantom pain experienced by his grandfather who lost his leg. When old Spencer walks to Alexandra’s grave, he had both legs.