Minecraft wiki entry for Frost_Walker, associated text: If moving on ground (not falling, jumping, or flying), any still water blocks with air above within a circle radius‌[Java Edition only] or square radius ‌[Bedrock Edition only] of 2 + level around the block being moved to transforms into frosted ice. This works only if the player is on the ground.‌[Java Edition only] The water blocks must also be on the same level as the block being moved to in order to become ice.