Used Ori Sickle, still got Ruined Fibre
When you are infight, you have a chance to fail the gathering. Not sure if intended, but has been like this forever. The chance is not very big though, I often mine while mobs wail on me during exploration =/
You were getting attacked at the time. You still have a chance of getting ruined gatherings if you’ve got some certain conditions on you (blind, confusion?) or perhaps even if you get hit whilst gathering. Only way to completely be safe for gathering is being out of combat.
There has never been a statement about whether it is intended or not but there are various conditions which seems to cause it.
1) harvesting while in combat, specifically getting attacked in combat
2) switching gathering tools in the middle of gathering, even if it isn’t the tool being used