Continuity mistake: In the episode "Missing Identity", when Spongebob is talking to Patrick about saying "hi" to him the first time, Squidward's house is gone.
Continuity mistake: In the episode "Plankton's Army", there is a group of Plankton's family sitting on top of the toilet when Mr. Krabs is first shown inside it. In two shots, the group has vanished from the top of the toilet.
Chosen answer: You need to provide a little bit more information to be able to answer a question like this. In what region is it not being shown? I see it being replayed here in Australia fairly frequently. As for a general reason, there does not appear to be any for why it specifically might have been taken off the air in any country or region. Like any show certain episodes can sometimes not be replayed for long periods for unknown reasons.
Lummie ★