This is where I'll put any short films starring The Simpsons, aside from the Maggie Simpson in... shorts.
The Good, the Bart, and the Loki (6:29)
Disney+; IMDb; TV Tropes; Wikia; Wikipedia
This was released on Disney+ on July 7, 2021. It's actually only about 4 and a half minutes, before the foreign credits fill out its runtime. So... Loki gets banished from Asgard to Springfield, where he begins living with the Simpsons. Bart gets him to zap Lisa to Asgard, where she picks up Thor's hammer and gains his power, then returns to Springfield to fight Loki. But of course there's a twist ending. There's also a mid-credits scene and two post-credits scenes, the second of which parodies the Disney+ series Loki. It's all pretty cool, if incredibly rushed.
The Simpsons in Plusaversary (5:21)
Disney+; IMDb; TV Tropes; Wikia; Wikipedia
This was released on Disney+ Day, November 12, 2021 (the second anniversary of Disney+). Moe's Tavern hosts a party for all sorts of characters you can see on the streaming service, but Homer's not on the list. When Goofy shows up without a "plus one", Homer takes that position. Meanwhile, some guests aren't enjoying the party, so Lisa Simpson sings a Disney-style song about Disney+. And... I don't want to say how the party ends. But the whole short is reasonably amusing.
tek's rating: ¼
When Billie Met Lisa (3:57)
Disney+; IMDb; TV Tropes; Wikia; Wikipedia
This was released on Disney+ on April 22, 2022. Lisa keeps trying to find a quiet place to practice her saxophone. Finally she ends up playing under a bridge, where she's heard by Billie Eilish, who takes her to a studio. Billie mostly hums the Simpsons theme music while Lisa plays her sax. Overall I'd say the short was just okay, but there are some decent visual gags.
tek's rating: meh and a half
Welcome to the Club (4:40)
Disney+; IMDb; TV Tropes; Wikia; Wikipedia
This was released on Disney+ on September 8, 2022. Lisa wants to become a Disney princess, but instead finds herself surrounded by Disney villains who sing a song hoping to convince her to become one of them. I like the concept, and I liked a surprise guest character who showed up early in the film (but which I won't spoil). But I didn't think the song was that good, and there was very little in the short that I found even mildly amusing.
The Simpsons Meet the Bocellis in "Feliz Navidad" (3:25)
Disney+; IMDb; Wikia; Wikipedia
This was released on Disney+ on Dec. 15, 2022. On Christmas, the Simpsons meet Andrea Bocelli and his adult son Matteo and 10-year-old daughter Virginia, and they sing "Feliz Navidad". That's about it. It wasn't bad.