This message means that the server is refusing to let you chat without enabling chat reports (i.e. disabling NoChatReports). If you have already disabled NoChatReports and are still seeing this message, then you really do need to reconnect.

You can get rid of this message by disabling the NoChatReports feature in Wurst and the reconnecting. However, this can be a very dangerous thing to do, as NoChatReports is a security feature designed to protect you from Mojang's deeply flawed chat reporting system. You should only disable it after you have read the chat reporting FAQ and are absolutely sure that you're comfortable with the risks, such as potentially losing your Minecraft account. These risks are not caused by Wurst, they come from Minecraft itself. The same things can happen in vanilla, it just doesn't warn you about it, which is extremely dishonest of Mojang.

Use the official feedback site:

• Give feedback on the chat reporting
• The most popular request for reverting chat reporting

You can chat when using the Wurst Client. It's just that Wurst protects you from chat reports by default. If you want to chat on unsafe chat reports enforcing servers, you can do so at your own risk by disabling the NoChatReports feature.

No! Never do this! Realms have by far the most aggressive form of chat reporting in the entire game. Mojang is constantly monitoring the chat on Realms and banning players without anyone even reporting them. This surveillance is outsourced to underpaid workers who do not care about the context of your messages. They are quick to issue false bans for anything that vaguely sounds like profanity. There are many known examples of this happening.¹⁾²⁾³⁾