In Bloons TD 6 , when an account is flagged for potential cheating or modding, a small leaf icon appears on the settings gear in the main menu. Being flagged leads to several restrictions:

You can no longer submit scores for competitive modes like Races , Boss Events , or Contested Territory .

Playing in a public match with a hacker who drops millions of cash can sometimes cause "splash" flagging for other players in the lobby.

Progress toward certain online-related achievements may be disabled. Common Reasons for Being Flagged

Having tools like Cheat Engine open while the game is running. How to Proceed What Being BANNED In BTD6 Looks Like!