When the in dark theme, the plugin keyword highlights in the script editor to be the wrong keyword color.
Expected result: The plugin keyword turns blue like the other global keywords
Actual result: The plugin keyword is red like the Lua keywords
See these two images:
Additionally, the plugin variable isn’t listed in the variable list when typing it: 
And the DebuggerManager variable doesn’t appear on the list nor has a color in the script editor.
Btw, the plugin variable was blue in light theme because it’s being treated as a Lua keyword (which is why it doesn’t appear in the list when you type it), and built-in variables and Lua keywords have the same color in light theme.
Edit: Didn’t realize DebuggerManager is deprecated, should probably be strikethrough in the developer hub.