Should mongos wait for prepared transaction majority committed when committing

MongoDB takes two phase commit when using sharded cluster deployment.
In the mongo/README.md at master · mongodb/mongo (github.com), it emphasize that,

Each participating shard must majority commit the prepareTransaction command (thus making sure that the prepare operation cannot be rolled back)

I know the point that majority committing is great thing to keep data safe. However, there is not any decription about whether the commitTransaction command should be majority committed. So I am interested in whether mongos should wait for it.