https://coderwall.com/p/x8xbnq/git-don-t-blame-people-for-changing-whitespaces-or-moving-code says:

git blame will show the author of the last commit that modified the particular line. If whitespaces were removed or that piece of code was moved around, blame will show that commit and you might blame the wrong person.

git blame -w -M

-w will ignore whitespaces and -M will detect moved or copied lines.