For me it was actually Crazy Rich Asians. Somehow I don't think I had seen anything of hers until it, but it was actually the movie that made me fall in love with her work.

Super solid romcom on its own (one of my favorites in the last decade, actually), but the writing and acting delivery of her character absolutely floored me. I was like, "who is this actress, why does she have such a commanding presence, and why have I never seen her before?"

(It also helps that I have been exposed to a similar community culture as the one depicted in the movie, with all the similar highs and lows, and her character is legit an archetype of real people I've met several times in my life. Where, and just as the movie depicts, you can't stand the antagonism and know it's wrong, but you can see exactly how it came about and almost can't blame them for being that way.)