I've come to irrationally hate a certain phrase in reviews: "it sticks the landing."
"Sticks the landing" is something said about gymnastics performances where the gymnast lands with perfect poise at the end. It refers to the many shows that FAIL in their endings. When we watch a long series (television, or franchise series) we are wondering if there will be a payoff, or it will end in disappointment: with unresolved plotlines, unearned victories, complete lack of understanding the work's themes, or just something that disagrees with our own interpretation of the series so far.
Famous recent embarrassing endings include: SW Rise of Skywalker, Game of Thrones, WandaVision, Enterprise, True Detective S1, some say the Wire or Sopranos, Seinfeld, Battlestar Galactica, and the overall fifth season of Babylon 5, Winter Soldier and Falcon. The fandoms live in dread of these ruining their last memories of the shows they love.
StL means a show has avoided that failure and is... fine. There is no sharp turn off a cliff at the 1 yard line. The villain you expected is defeated, possibly at a high cost including some lives of the main cast, the themes and mood carry through, and basically everything you expected would happen does. It can even be some of the most touching moments and best action of the entire series. It's satisfying AND reassuring.
Famous recent landings stuck include: SW Revenge of the Sith, Breaking Bad, West Wing, Farscape, Fargo seasons, Avengers Endgame, HBO Watchmen, the Expanse, Deep Space 9. I'd even say Lord of the Rings and the Wheel of Time books.
They all were fine, and for being fine, they received lavish praise because they avoided disappointment. And it's about these shows that I hear the phrase "stuck the landing."
I don't think the phrase is wrong. It seems to accurately describe endings that satisfy and don't disappoint, in a way a gymnast's final moment should. It demonstrates a minimal level of skill and awareness of your work.
I just also think that level is unambitious for what a true work of art should be trying for.
There is a third type of ending that is the key to interpreting everything that came before. These are endings that re-contextualize all of the series so far, or are vital to understanding the work. This is fairly common in scifi or fantasy where there is some Metaphysical Secret of the Universe that will be revealed, or crime/mysteries where you find out whodunnit at the end, though it's not universal in either genre. It can just be the revelation of the psychological dynamics of a character that shows this was always going to end as a tragedy, or even just enough emotional pathos that you realize the point was the character's journey and not plot. They can sometimes be confusing to the audience, who expected a neat conclusion and didn't get it.
Recent key ending examples include: SW Return of the Jedi (and redeeming Anakin), the OA (both seasons), Utena, Evangelion, Arcane, Twin Peaks, Star Trek TNG maybe, the Boys S1, For All Mankind S3, the Leftovers, A Place Further than the Universe, Outer Range, the Sandman and Watchmen comics, Station Eleven, all the good Mike Flanagan stuff.
The ideal case is, once you've seen a key ending, you immediately want to rewatch the entire series to see all its scenes again now knowing the proper context.
And while the line between "embarrassing and StL endings" may be fuzzy, and the line between "StL and key endings" is also gray... you probably have noticed whether an ending ends up in "embarrassing or key" can be a hard question. Sopranos and Seinfeld were certainly trying to make a re-contextualizing "statement" about the whole of the show in their final episode... but largely just ended up annoying people.
I highly value a good key ending. It's "informationally dense" telling me major things I didn't already know. And it requires intricate buildup in all of the episodes before for the payoff to "make sense."
By contrast... StL episodes bore me. If I like your characters and moods I'll probably be fine watching, but I don't actually have to "find out" that they defeat the villain and maybe a main character dies. Lately, I've even stopped watching the final parts of a series because I just don't care. I'll stick around to find out a big revelation but "they did in fact save the day, but at a price" isn't it.
There's a lack of ambition to sticking the landing. It's about serving a product. A key ending would be if the gymnast revealed they were upside down the whole time and bungieing from the ceiling.