Some different Bash looping options.

for-each.bash

find -not \( \( -name node_modules -o -name .git -o -name dist \) -prune \) -type f -name \*.css|

# a
while IFS= read -r file; do git mv "$file" "${file%.css}.less"; done

# b
xargs -rd\\n -i sh -c 'git mv {} $(dirname {})/$(basename {} .css).less'

time while IFS= read -ru9 -d $'\n' line; do
  echo -n "$line"
done 9< <(ls -1)