I was trying out a datapack that would keep the spawners data when broken with silk touch, and before I finished testing it out and working out any issues I noticed that while it would keep it's custom data when broken, if you placed it down in survival it placed as a default pig spawner instead of with the custom data. I tried it a few times and no matter what in survival this happens, but as soon as you place a spawner with data in creative all works fine. Seems somewhat intentional however this is disappointing if so because that kinda removes map making and datapack potential.