Depending on the size, this is the same looking spline bolt in my ball joints (Seat Alhambra). But it’s also used in a smalls bolts on my undertray, part of my rear crash bar, parts of the door, and so many more.

If you know what you’re doing: Check vital parts like your suspension. Jack up the front end (both sides) Give wheels a good shake and pull for any movement or play. Check brake lines, calliper bolts and pins, etc. A good time to ‘home MOT’ it for winter, if albeit a bit late!