That’s entirely different from if you’re engaging meaningfully in a language and culture and it’s the right time and place to share it with someone.
You’re at a dumpling restaurant and someone says ‘here’s a dumpling.’ You say, ‘I really like these dumplings! I had them when I visited Taiwan!’ In Mandarin. They thank you and say oh cool you know some Mandarin! They walk away.
A service worker isn’t your language tutor. Go to source country and do that shit, or hire a tutor on italki who can praise you for knowing two words and then can teach you more. Pay them.