Seen it a couple of times. On both occasions the problem lay with a non-stainless component that had pitted and / or rusted and during use the rough surface of the component has over time rubbed through the material
Could little bits of rust have gotten into the fabric and that continued to wear it out? Or enough damage was done that my continued use pulled it free? I only ask because my rig is relatively new ( <1 year ) and though I can't really inspect the ring anymore since I lost all of that, I'd be really surprised if it was my ring that was pitted and rusted.
Can't really help other than to say that I have seen the ring cause wear and also the rapide link cause wear. This is why I prefer cost links to attach bridles where there is not a larks head system at the bottom of the bridle
Perhaps discuss with you rigger or the person who assembled your rig. They may remember something
Brown discoloration makes it look like rust damage.
The next most likely cause is a rough edge on a hew ring. Every year , a tiny percentage of rough hardware sneaks out of forging mills and parachute hardware. This why it is always a good habit to ask a rigger to inspect and assemble your brand new gear before you jump it.