Yellow Square
This is a square, which looks like a yellow card. This emoticon can be used to indicate anything yellow, such as the yellow card in the hands of referees in football matches, which means warning to players who violate the rules.
Different platforms depict different square patterns. The squares depicted on most platforms have four right angles, but in the emoji of Facebook platform, the four corners of the squares have a certain radian, which makes them look relatively smooth. In addition, the square depicted by Emojipedia platform has a strong three-dimensional sense and presents a certain luster. Microsoft and OpenMoji platforms, on the other hand, draw black edges around the square, which makes them look more conspicuous.