Chink in the armor is a very common phrase. I never even thought of it as a slur.
I didn’t either until 2012. Apparently this poor dude didn’t get the memo.
Not even never was racial or ethnic,sorry libs not this time:
https://www.merriam-webster.com/dictionary/chink
It isn't. It means a gash, crevice or a flaw. It has nothing to do with race.