Earlier quoted context omitted.
So apparently the tool is slanted toward American English where the non-word practise is properly treated as a spelling error like colour . If you use these words in writing for Americans and you are not a citizen of the British Commonwealth, you instantly mark yourself as arrogant.
> and you are not a citizen of the British Commonwealth What do you regard as the British Commonwealth, and what variant of English spelling to you expect people to use who are not part of this grouping? Just so that you know, in case you don't, "US English" is used just about exclusively in the US, and UK English is used in most of the rest of the world, despite the fact that most of our devices incorrectly default…
To be sure, I don‘t have any dog in this fight, just highlighting a fact from my experience that many here might not know.