This is the series of incantations that eventually worked for me based on this link suggested by @robertklep and @vovkasm.
brew uninstall --force node
brew uninstall icu4c && brew install icu4c
brew unlink icu4c && brew link icu4c --force
brew install node
I’m not sure if they’re all needed, but given that I can’t get my machine in the previous state… I’ll just leave this info here, maybe it’ll be useful for somebody else.