red-flagged
/ˌrɛdˈflaɡd/adjective
1Bearing or flying a red flag; specifically bearing a red flag as a symbol of revolution, socialism, or communism.
2Chiefly North American. Identified (sometimes with a red flag or marker) as a cause for concern or as warranting special attention.
Origin
Late 19th century; earliest use found in Mary Braddon (1835–1915), novelist. From red + flagged, after red flag.