My keyboard shortcut is "Ctrl + D", but I don’t know where or which command overrides it. I guess this is from the plugin.
How can I see what Ctrl + D is now mapped to?
Open the console ( Ctrl `) and enter sublime.log_commands(True). Then type Ctrl + D (or any key combination) in the editor to see the corresponding command printed on the console.
sublime.log_commands(True)