There was an iPhone user who got locked out of his device because the pin pad Unicode changed and one of the characters he used was no longer available. I forget what language he used, I want to say Serbian but am likely misremembering that.
I’m going to hazard a guess that it might be Romanian. Romanian has the letter ș, which is an “s” with a comma beneath. Wikipedia. It wasn’t part of the Unicode standard until 3.0, so people used ş, which is an “s” with a cedilla.
I have the modern Romanian keyboard on my phone, so I can easily type ș, but not ş. I can see how that would have broken during the changeover to Unicode 3.0.