Snow Golems are able to generate snow beneath themselves even if not touching the ground. The easiest way to see this is to attach a Snow Golem with a lead to fence that is a few blocks off the ground.
MC-214344
Snow Golems can place snow when not on the ground
Open
7
(Unassigned)
Confirmed
(Unassigned)
OnGround, place, snow_golem, snow_layer
1.16.5, 21w05b, 21w06a, 21w07a, 21w08b, ..., 22w15a, 22w17a, 1.19 Pre-release 2, 1.19, 24w34a
Retrieved
The same thing happens with sheep eating grass. Zedaph made use of this bug to build a sheepfarm with floating sheep. Don't think this bug needs to be fixed.