Its absolutely not allowed and we have tech in place to prevent it. If you try to type these words it will not send to anyone, it will instantly flag you for report/investigation, and it will possibly restrict all usage of chat on that account - automatically.
People who are doing this are using special characters, spaces, or other such things to break up the string so that they arent actually typing the slur, but it reads as the slur.
This is an insta perma ban if we receive a report about this, and any reports/screenshots we see of this on social media are taken seriously and investigated quickly - very likely leading to bans.
We are actively looking into more tech to help detect this, but its not an easy concept. We are talking machine learning and more complicated algorithms that would be needed to help detect this on such a massive scale with less false positives.