If only. It was completely taken over by the empire. Darth Vader’s throne is built on Mustafar and the planet was used as a mass grave for the dead from the Great Jedi Purge, as well as serving as the location in which Inquisitors were created, specifically taking force sensitive infants and training them there. It was also used to replace the cloning facility lost on Kamino. A bit after all this Vader is given the planet and connects with a Sith Ghost who helps him build a temple to harness the unique force energies from Mustafar to (edit) try (end edit) bring Padme back to life.

Most of this happens in the Darth Vader comics, however Mustafar does show up again in an arc of Rebels.

(I know this is just meme I just thought it was interesting that there was a fair amount of importance for Mustafar and was used surprisingly well for canon development. We just didn’t get to see any of it in animation/live action)

Mustafar was shown in Rogue One, specifically Vader’s Castle. It was also the planet at the very beginning of Rise of Skywalker where Kylo Ren slaughters all of those people and gets a holocron, or something.

“Yeah, but at least we can cut our losses and sell the planet”

As it turned out, this would not happen.

You don’t think they carried insurance that covered Acts of Jedi?