I figured that. Also one of the official definitions for the word "minority" in both UK and US dictionaries is an ethnic minority. Therefore when people in the US look at the word in context or even when it's ambiguous that's a valid meaning.

UK - Oxford https://www.lexico.com/definition/minority Def 1.2

A small group of people within a community or country, differing from the main population in race, religion, language, or political persuasion.

US - Merriam Webster https://www.merriam-webster.com/dictionary/minority Def 3a/b

a part of a population differing from others in some characteristics and often subjected to differential treatment

Thanks for these sources, English is not my first language but I get how could have been perceived insensitive.