With the following code everything appears to work correctly:
var You = L.latLng([500, 500]);
L.marker(You, {rotationAngle: 25}, {rotationOrigin: [32, 33]}).addTo(map);

Now, by adding an icon and passing it as second argument, the rotationAngle appears to have no effect:
var You = L.latLng([500, 500]);
var greenIcon = L.icon({iconUrl: 'favicons/tarkov/Legend/green-icon.png'});
L.marker(You, {icon: greenIcon}, {rotationAngle: 25}, {rotationOrigin: [32, 33]}).addTo(map);

btw the green icon looks that way by default as png. it didnt rotate at all.