I am told the same thing, but to me the voice now feels more natural and some qualities of it have changed. Before I was pushing up the pitch, now I just can relax into it. Timbre has changed, laughs and such have changed - so I am good with it, even though admittedly I am not having those huge big changes that some have experienced, but I did not really expect that.
Careful about the whole thing regarding "There is a surgeon XY that does the same procedure as Yeson". The basic procedure is over 20 years old and was "invented" by a guy called Wendler (I believe from Germany). So its called a Wendler glottoplasty. Since then a lot of surgeons learned that method and used it. It was considered a procedure that has considerable risks of loosing the voice, of getting hoarseness and raspiness permanently, of ending up with a too high or forced sounding voice.
Only recently it seems that further development in the DETAILS of the procedure and improved skill and precision by the surgeons have made this method viable. So I would always check thoroughly what the details are and most of all what results have been created so far by that surgeon. I did not go to Korea for the surgery because I thought he is the only one doing this. I was aware of at least 3 people doing this in Germany at that time, but I decided against those becaus eI heard bad voice samples, bad reports, had a consultation with one one them who said it has only a 30% chance of improvement of the voice (30% no change, 30% getting worse). At least he was honest about not being able to give good results even though the basic method (suturing vocal folds) is the same, his precision and the details of the technique are different from Dr Kim. So I chose to spend 8000 EU instead of getting it done on NHS for free.