The letter "Ё" (yo) is unique to the Russian alphabet

https://nyc3.digitaloceanspaces.com/keyb/rus/from-qwerty-to-jcuken-transitioning-to-russian-typing-made.html

The letter "Ё" (yo) is unique to the Russian alphabet, representing a distinct sound that can change the meaning of words if omitted or mispronounced