Lines with a 🔴 red background marked with a minus sign ➖ are removed at that step.
Lines with a 🟢 green background marked with a plus sign ➕ are added at that step.
Sometimes lines are newly added or totally removed, but quite often an added line is a modified version of the removed line. For example, in the screengrab above, line 2 and line 8 are new but all other added lines are a modified replacement for the removed line above it.
tar.gzlinks for that tagged commit.