It is never mentioned or implied in the film that the Wayfinder belonged to Anakin specifically.
It was on Mustafar, stated in the novelisation, stated in the deleted scenes, and the current Darth Vader comic has him acquiring it directly.
The Alazmec of Winsit, whom Kylo Ren fights to obtain the Wayfinder, are a cult following Vader.
I said it wasn’t stated in the film; one shouldn’t have to go outside of a work and rely on ancillary material in order for it to make sense.
It’s pointing out that Anakin’s Force Ghost could’ve told Luke where his Wayfinder was, basically pointing out the massive plot hole in The Rise of Skywalker.
My gripe with this is,a character not telling another character something isn’t a plothole. By this same logic it is a plothole in A New Hope that Obi wan didnt tell Luke that Vader was his father and that he had a sister.
I wouldn’t frame it as a plot hole, but more of an Idiot Plot. On the topic of Obi-Wan, the reason he didn’t tell Luke that Vader was his father is so he wouldn’t be traumatized.