When you are in the settings and setting the difficulty, the values will begin with lowercase letters, "easy", "hard" whereas before they were "Easy" and "Hard". They also ignore the current language setting.
Linked issues
is duplicated by 5
MC-121652
Difficulty settings are lowercase
Resolved
MC-121702
Difficulty names have no capitals
Resolved
MC-121704
Difficulty Bar Capitalization
Resolved
MC-122250
Difficulty Level Text isn't in capital (Difficulty: normal ===> Difficulty: Normal)
Resolved
MC-122855
Game difficulties are in all lowercase
Resolved
Confirmed for 17w46a.