YouTube used to demonetise profanity unless it was mild. YouTube would demonetise profanity in the first X number of seconds of the video. These rules change and have been relaxed of April last year, but generally these rules still exist.

There isn't a hard filter if you say "suicide" you automatically get it. However it increases the likely hood of demonetisation. So people avoid it to be safe. So you end up with people using stupid euphemisms all the time.