A triangular red flag on a post. Most commonly associated with golf, as shown in the flag in hole emoji. Can also be used to represent the term red flag, signaling a problem or issue.
Triangular Flag was approved as part of Unicode 6.0 in 2010 under the name “Triangular Flag on Post” and added to Emoji 1.0 in 2015.
U+1F6A9
? Triangular flag on post