A creeper dropped Pigstep after a skeleton killed it on a realm. I thought that you were only able to obtain Pigstep in survival by getting it from a Bastion yet I was able to get it the way you usually do music discs.

I am pretty sure this is a bug however it could not be, I have watched lots of 1.16 update videos and all say Bastions are the only way to get the disc, in which case the way I received it was a bug.