At https://engineerfix.com/how-to-tell-which-way-a-fan-is-blowing/ we are told that

"Most fans feature two distinct arrows placed along the side of the casing,

which relay critical operational information."

(not true in my experience) and furthermore,

"One arrow indicates the direction in which the blades rotate when the fan

is powered on, which is usually a clockwise or counter-clockwise path."

(so, unusually, the direction is ??)

Leslie