The Krabby Patty That Ate Bikini Bottom/Bubble Buddy Returns - S8-E15
Continuity mistake: The giant Krabby Patty eats SpongeBob's shoe and sock in the kitchen. But by the time SpongeBob and Squidward run to the door and are stopped by Mr. Krabs, the shoe and sock have magically reappeared.
Mermaidman Begins/Plankton's Good Eye - S8-E22
Continuity mistake: When Plankton tries to open the safe, his arms come off. The arms stay on the safe. But when Mr. Krabs approaches the safe in the next shot, Plankton's arms have disappeared from the safe.
Ghoul Fools - S8-E24
Continuity mistake: When Squidward is sucked into "The Void", the bag of money that he was holding vanishes in the next shot.
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 ★