Changing this to insert zero-width spaces is also not universally acceptible, as there may be things in web content which users should be able to copy paste without unintended effects. This leaves no ability for a bot to take in web content, such as from RSS feeds without removing all characters, which changes the intent of a message. With this being the case, the above definition about it happening only with invalid Unicode characters, or with characters with unexpected formatting is clearly not correct.

However, the behavior of collapsing characters has been observed with NFC-Normalized Unicode with all control characters pre-processed out. For example, to prevent unexpected mentions you could consider stripping characters or placing a zero-width space (U-200B) after them. If you are passing user-generated strings into message content, consider sanitizing the data to prevent unexpected behavior. The only current documented guidance on this is the following:Р”Вiscord may strip certain characters from message content, like invalid unicode characters or characters which cause unexpected message formatting. Please clarify the exact sanitization process for messages.

Normalized classes discord plugin