Very cool! I shot a slightly piebald doe about 5 years ago, but havent seen one since... Probably the only one I will ever see, to be honest.
We recently posted an article about piebald deer on our site... after a bit of research, it looks like only about 2% of deer are piebald and that for a fawn to be piebald both parents need to be as well. Pretty crazy stuff.
https://backcountryjunkie.com/journal/piebald-deer/