https://www.ion-products.com/water/men/neo-accessories/neo-hoody/It's a loose hoodie top made out of neoprene material, intended to use as a windshield and extra warmth... it's got cutouts for the spreader bar hook...This is the first one i found online, but there are different brands etc. Local kite shop at St Kilda in Melb sells them too... (not affiliated with any brands, just trying to understand how it impacts riding before buying one).
You can wear it on top of existing wetsuit too... i think would be helpful on chilly spring/autumn afternoons when you wear shorty to give you wind chill protection and minimise risk of hypothermia after prolonged session (been there

)