Empire Strikes Back
Luke is full of the optimism from the first movie, and is a war hero, and the first thing to happen is he gets smacked and dragged off by a monster. when this happened in Star Wars, Obi Wan was there to save him from the sand people. instead, he only shows up later as a ghost after Luke has already freed himself. Luke is on his own now. instead of giving him help he gives him a task, to be trained by a wise master.
Yoda was set up to be a master jedi and "great warrior" and this was turned completely on it's head. he wasn't even a serious old hermit, he was bopping Luke on the nose and stealing his food. he was acting foolish rather than serious, and it was endearing. war does not make one great, something the war hungry youth from the first movie fails to realize. here Luke/Mark has to live with nature, to live alongside the snakes and lizards of the planet, just as he has to live with Yoda and eat his shitty soup. the force is now about a more holistic, universal thing, rather than powers weilded by individuals. whereas in the first film Obi Wan instructed him to stretch out with his feelings, here Yoda advises a more hermetic approach, tuning in to the feelings of his surroundings, subduing his own will temporarily for the proper application. controlling his feelings rather than letting his feelings control him. the first movie was all about excitedly wanting to rush off to adventure; now it's about patience, per Yoda's warning.
the force, Vader's importance & the reveal of his scarred skull, the grotesque video strangeness of the og Emperor's first appearance, everything from the first film is heightened and twisted. a shadow is slowly cast over a Star Destroyer in the way that a Star Destroyer cast one over another ship in the opening of first film, only to reveal the massive, comic book style multi-colored Super Star Destroyer, the deep blue lit from behind by bright red engine lights. Vader's first kill is when he chokes out someone at the end of a video conference call -- now the force can work across distances -- Obi Wan projecting himself on Hoth and Dagobah, Leia & Luke & Vader all force txting one another, etc. none of this was really in George's og depiction of the series, and the new approach left a lasting mark on the mythology that the series still struggles to escape from. the prequels Jedi feel so weird cos it's a reversion to the idea of Jedi from before Empire. Empire's depiction leaves such a lasting impression.
Yoda's spookily lit "there is another" speak was initially meant for the Sequel Trilogy that followed a far different version of ROTJ. it was to be Luke's twin sister training across the galaxy and coming to him as an old Jedi hermit for training, pretty much what TLJ ended up being. kind of makes the claims that they threw out all of Lucas's ideas seem a bit iffy imo.
so Luke ignores Yoda and rushes into war anyways and suffers for it. the two white male lead heroes from the first one end up dismembered and crying for mercy / imprisoned and sold as an object. Luke and Han won the day together at the end of Star Wars. here they fail, they pay for their hubris, as both Luke & Han think they can save everyone. they are in the clouds, in the heavens, but they have driven themselves to Hell. it is up to Leia and Lando to save the day, and ultimately, the galaxy.