Another yukkuri's trademark. Used as their version of a scream or for when they're panicking, scared, surprised, confused, and it's also used as their crying sound. Essentially, it's the sound they instinctively make whenever they get into an uneasy situation.
There are a few cases where a yukkuri uses yunya to express happiness (e.g. post #85425) but these are extremely rare. It's almost exclusively used on unpleasant situations.
If you see this ゆんや then this is "yunya"
If you see ゆんやあああああああ then it's "yunyaaaaaaaa"