Generally, each of the bindings Ctrl+a, Ctrl+c, Ctrl+v, does what it is supposed to do (select all, copy, paste) but then inserts the character that was pressed with Ctrl.
For example, pasting "Hello" to the chat will actually write "Hellov".
Copying a selected text will also replace it with the letter 'c' after copying.
And Ctrl+a cannot be used because it will replace all text with 'a'.
Basically the Ctrl+[char] binding will act as if the user pressed [char] right after pressing Ctrl+[char].
This issue might exist in earlier versions too but it doesn't happen on 1.8.9 or earlier.
BTW, I am using java 8 and not 11.