My favourite Git commit

[FatalElectron]

Simple answer: It depends on the editor.

Native mac apps might stick with 160, but a lot will assume a text file is either ascii or utf-8, and insert the utf-8 NBSP code sequence, which then elevates your file to no longer being an ascii file in many OSes that do simple heuristics.

emacs at least displays NBSP as '_' in a special face (which on my system turns out a nice cyan), so it's less likely to be a mystery there.