/execute as [other player] can be used to impersonate other players in chat

If you have operator permissions, you can just enter /execute as [player name here] run say [message here], and it will appear in chat like the person actually wrote the message, this is a problem, as you just can make any person say something bad, and then report them to get them banned.

I currently can´t attach a video clip or something else

I set it to private so nobody with bad ideas will ever see this and abuses it to get people banned