“Thank you” in someone’s first language lands differently. It says you tried to meet them where they live.

Gratitude in somebody’s own language arrives in the part of them that is not working. All day they have been translating, adjusting, staying slightly on guard, and two familiar words set that down for a moment. The accent makes no difference; the effort is the entire message. It says you noticed where they are from rather than treating them as a function of their job.

Learn it for the languages you hear around you, from whoever serves your food or cleans your school. Use it without making a performance of it. If you get the pronunciation wrong, ask them to fix it.