There was a bug that caused it to do a lot of unnecessary allocations though. That was fixed a few weeks back. Have you updated your runtime recently?
I'm looking at the profiler with the latest 3.4 runtime on various skeletons and I'm not seeing any alloc on SkeletonRenderer.
It's true though that there is an unavoidable allocation in certain situations, like when you use multiple submeshes (from using multiple materials) and keep switching mesh attachments or reordering the draw order. But even then, it shouldn't do it every frame unless you change the attachment composition every frame.
