It seems to redirect in the browser to the / version, and then remove the slash a moment later.
https://www.wikijob.co.uk/content/interview-advice/competencies/communication
goes to https://www.wikijob.co.uk/content/interview-advice/competencies/communication/
and then to https://www.wikijob.co.uk/content/interview-advice/competencies/communication
I’m not able to reproduce this on my localhost. What’s going on here?