why does castillian Spanish pronounce z as th

One story I have heard is that a certain monarch had a lisp, and in an attempt to keep from embarrasing him, the habit spread to the court, then the nobility, and then society at large. I suspect this is nonsense, but it is at least, widely believed nonsenth!

🤣

a man with glasses and a mustache is making a funny face and saying yeth .

ALT: a man with glasses and a mustache is making a funny face and saying yeth .