Museums have a ton of stolen artwork in them, that’s why I brought it up, but modern acquisitions are typically legitimate (in the sense that someone was paid for making art and the museums have the right to display it). Dead people can’t claim copyright, but their living family members can, at least for 70 years after their death. If a living artist sold a piece, and it gets put into a museum, they no longer have a say as to what is done with that art, since they typically sell the rights along with the painting. I know that most at purchases/donations to museums are corporate money laundering, but art really isn’t being stolen by museums at large anymore, and the general public has a problem with the artwork in museums that is stolen.