I think the key new context here, for those that don’t care to follow, is that he’s having his titles stripped (including Prince). This is in addition to the earlier move have him not officially use titles like Duke.
Whereas Mountbatten was formerly called Battenberg (since Germany declared war on them in WW1), and for the same reason Windsor was formerly called Saxe-Coburg and Gotha. Which family really is the House of Wettin (the saxony kings). Who was my latest landlord.