ahem “In the former film, the deceased Sith lord, still in his full black armor, is set ablaze atop a funeral pyre on land.“ Anakin appears as a force ghost at the end of the film alongside fellow Jedi Obi-Wan and Yoda. In the case of the others, we saw in the films that their bodies vanished as they died. There is every reason to think that Anakin’s body similarly vanished off-screen and the funeral pyre was just to…
Also note though that Obi-wan and Yoda are already standing there and force ghost Anakin fades in next to them after the funeral pyre has already started. So was Anakin still slightly alive and body intact when Luke started the funeral pyre and it was only at that point that he actually died?
Maybe the force ghost visibility power didn’t come so naturally to Anakin, maybe he also just took some time to decide on the apparent age of his ghost