When joining curves, the resulting curve will inherit the bevel depth of the active curve, but the radii would stay the same which leads to changed appearance when joining. Now compensate for this taking the different bevel depths into account (if present). Was a feature request here (and I also think we had reports about this -- which were usually turned down as not-a-bug): https://blender.community/c/rightclickselect/bhhbbc/ Differential Revision: https://developer.blender.org/D10752