My two old ladies got this when they grew older. Marley lost nearly all the hair on her tail, it started with just a small circle in the middle of her tail and just seemed to spread out. It didn’t bother her or the vets, it just didn’t look very nice. Stevie (her litter sister) also developed a bald spot in the middle of her tail but it started later than Marley’s and thus didn’t get the chance to spread out. Both girls had a half dock so baldness was limited to the shortness of their tails. Both my girls were spayed after their second season so don’t think it was hormonal in their case.
Luckily the appearance didn’t stop their tails from wagging or bother them in the slightest.
Cherish every moment with Morgan (as I am sure you do). I won’t ever get over the loss of Marley and Stevie as they were so special to me.