Where does “shirk” come from?

I can't write this etymology summary because the chain provided is circular and repetitive (cycling between English shark and German Schurke), which doesn't establish a meaningful etymological pathway. Additionally, the known meaning is listed as "unknown," making it impossible to explain sense development as required. A valid etymology requires a linear chain showing language progression to an origin point.

shirk (English): To avoid, especially a duty, responsibility,...