In Tutorial, run ends when the game says complete. The timer SHOULD stop whenever you finish capturing the point. For example, in SM64 the timer ends when you grab the last star, you don't stop after the cut scenes, so i believe it would make more sense to end the timer the frame it finishes capturing the point.
In most speedruns, timing ends when you lose control of your character. Also the tutorial doesn't technically end until "complete" pops up. FYI you can personally time your run in whatever way you want. The specific timing is only needed when submitting a run to these boards.
With Overwatch 2 finally going live, this means that our Overwatch 1 leaderboards are all pretty much legacied. All new speedruns should now be submitted to the Overwatch 2 leaderboards, here: