In their example & imho, "Phrases in green have been marked to show passive voice." communicates their intent better than "We marked in green phrase using passive voice". The 'we' is useless.
That's still flagged as passive voice by this abomination of an editor.
> Phrases in green use passive voice.
The meaning of that is less clear than the original. The phrase isn't using anything. We are talking about how it was written: facts about its construction that happened to it. The only way we can do that honestly and concisely is with passive voice because the phrase is only passively involved.
Rules like these are toxic nonsense.
True in English, too.
It's a common bad-writing problem in English that it is frequently used improperly so that it obscures meaningful bits while being excessively verbose. Thus, common neophyte advice is “avoid passive voice”, and some people get super religious about this without understanding what problem the advice aina to solve.