Anyone who thinks that Star Wars has only now in 2018 “jumped the shark” has selective memory loss, and is forgetting the years 1999 and 2002 when Jar Jar Binks and a flippy jumpy Yoda graced out eyeballs, respectively. There’s honestly nothing at all in the new Disney movies that fits the phrase, especially as they hew much closer to the more grounded and believable nature of the original films. Just because you don’t like a scene or a film doesn’t make it a “jump the shark” moment.
I don’t think you’re going back far enough. Death Star II, Luke and Leia being siblings, and the Ewoks could arguably be considered “jump the shark” moments.