There's a report button for stuff like that
An unsolved pain point at chess.com
If you're receiving abusive chat, you should report and block.
https://support.chess.com/en/articles/8562517-how-do-i-report-someone
Alternatively you could disable chat.
As to the Russian flag, other than what is posted in the following article the discussion isn't allowed in the forums.
https://www.chess.com/article/view/on-the-invasion-of-ukraine
people! I do not understand? Why do Israelis have to suffer on chess.com why every second game there are Palestinian responses? chess.com needs to address this urgently!! Another question, why did they cancel the Russian flag and the Palestinian flag? By the way, anyone who supports Israel will not lose from this!! The nation of Israel is alive and well! And we will suffer as much as we need to as we have suffered in the past and survived everything! Holocaust, crusades, enquisition. pogrom So support the Jews and you won't lose!