Are most usernames case-sensitive?

Yes of course , e.g. Wikipedia user names are case-sensitive.

Anything that is case sensitive discriminates between uppercase and lowercase letters . … For example, if a password field is case sensitive, then you must enter each letter case as you did when the password was created.3 Şub 2022

Passwords are case-sensitive to better protect your login information, while usernames are not . This means the system will recognize your username, regardless if there are capital letters or not. Passwords won’t be recognize unless it is entered exactly as it was created.

Unlike function and class names, variable names are case-sensitive. Most modern languages are case-sensitive; some older languages are not. In contrast, variable names and labels are case-sensitive. Variable names are case-sensitive alphabetical string without spaces.