Not really a bug, & not sure if it is done on purpose or not, but the members link has been spelt as membres. The r & e round the wrong way.
More aboutspelling mistake
What you are seeing is the "French" side coming through. BoM is a French company where the base/main development team for the forum / site is out of. Members is spelled Membres in French. You'll see a few other little things similar around the site, if you look closely.
Thank you. Like I say, wasn't sure if it was deliberate or not, but thanks to your explanation, I now know it is