To repeat: Millions of videos are posted online every day. It would be impossible to catch every one that is breaking policies.
I never even heard of that video until you brought it up.
You also still do not understand how COPPA works. Being COPPA compliant means the channel is labeled as kid friendly and the videos on it are kid friendly. It also means that the videos will appear on the YouTube Kids app, which is separate from the regular YouTube app.
This video is not labeled kid friendly, so it can have vulgar llanguage. If you consider it to be too offensive, you can always flag and report it.