However, a quirk in the way Unicode handles emoji has meant that some of the symbols take up many more characters than others. For example, a flag can take up as many as 14 spaces in your Tweet. Twitter has announced that it's changing the way it counts emoji so that they're all counted equally, as two characters. - https://www.theverge.com/2018/10/11/17963230/twitter-emoji-c...
So 4 character flag, which is written as 1 character, is sometimes counted as 2 characters. Honestly, I don't know, I did not expect for this to go so deep.