The chat filter will often censor messages seemingly randomly, even when turned off in the settings. You can see in the attached gif that "L4R4" was censored, but "L 4R4" and "l4 r4" are both fine. You can even see that earlier in the chat history I was able to send "L4R4" without issue.
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If you put a space before the word it doesn't censor it most likely why you saw it uncensored before, this issue with chat censoring the most random stuff has been going on since light fall, the game has the option to censor chat anyway but Bungie decided in all their wisdom to force it on regardless of your choice, it was supposed to be Bungies way of protecting people but all it's done is make it harder to communicate, especially for deaf people, bosses, encounters, even directions such as "dunk the ball" get censored, it's about time Bungie switch it off and let us make our own decision with the filter setting.