Someone learning your language is doing work you may never have to notice.

Someone speaking to you in your language rather than theirs is doing continuous work, translating, second-guessing, losing nuance, sounding less capable than they are. That effort is invisible to you because the whole point of it is that you get to be comfortable.

Slow down slightly, avoid idioms, and do not confuse someone’s fluency with their intelligence or expertise. If you can, learn a few phrases in their language, badly. The gesture matters less for its usefulness than for briefly putting the effort back on your side of the conversation.