The original design of Pikachu never had any black details on its tail, yet it also had a stripe or a zigzag pattern in the past to people including myself : r/Retconned

Pikachu's Black Tail and the Mandela Effect

Pikachu's Tail Was Never Black! (Mandela Effect Explained)

Board 8 Ranks Generation III Pokemon, Board 8 Wiki

Pokemon's Black Tail Pikachu Mandela Effect Explained

Pikachu's Black Tail and the Mandela Effect

Pikachu's Black Tail and the Mandela Effect

Pikachu's Black Tail and the Mandela Effect

Pikachu has no black on his tail circa 1998 : r/Retconned

Pikachu's Black Tail and the Mandela Effect

Why did they get rid of Pikachu's black tip on his tail in Pokemon? - Quora

Why did they get rid of Pikachu's black tip on his tail in Pokemon? - Quora

Pokemon's Black Tail Pikachu Mandela Effect Explained