This is really funny and I do feel ashamed for my laziness.
I didn't expect ChatGPT to make such trivial mistake, although, I have no idea which model do they use on the free plan these days.
The correct code is, of course:
text.replace("—", "\U00010EAD\U00010EAC")
...in case anyone is curious.
Curiously enough, after telling it "your code is broken, can you find the mistake?" it was able to correct the code: