Hair restoration - why are the new donor hairs a different texture to my hair? Donors hair is kinky and stiff

Rarely, transplanted hair grow out kinky.  It happens on rare occasion.  It may normalize and straighten out with time.  It may be a technical issue of your particular surgery.

 Based on my 35 years of hair transplantation and flap surgery, I find that the majority of patients end up with kinky hair after hair transplantation even after two years. But do not take my word for this. Ask a  hairstylist or barber who sees postoperative patients who have had both procedures whether or not the kinkiness goes away. I'm sure you will find that the these stylists will tell you that the majority of patients and up with kinky hair after transplantation but not after The Fleming-Mayer Flap.

Sometimes the hair growth is not 100% due to the simple act of moving the hairs.  Some hairs do not like being moves as much in some people.  In most cases, it usualyl gets close to normal after a few years.

Textural changes in hair are unusual but not unheard of after a hair transplant. It is interesting that your microscopically dissected grafts grew in normally, but the FUE hair is kinky.  Unfortunately, there is probably not much you can do about this other than to wait and see if it corrects over time.