"Dynamax Power" isn't a move's maximum base power. Lifted from Bulbapedia, Dynamax is a temporary transformation affecting Pokémon that was introduced in and is exclusive to the Generation VIII games Pokémon Sword and Shield.
When Dynamaxed, all of the Pokémon's moves will turn into Max Moves that correspond to those moves' types and categories. Dynamax Power refers to the base power of a Max Move that is called as a result of (in this case,) Triple Axel.