The 🅱️ emoji shows the letter B in a red square. It is used for a second option, a B grade, or became popular in memes as a replacement for the letter B.
Usage example
I guess it's the 🅱️ option
🅱️ as in second option
⚙️ Technical▼
Unicode1F171-FE0F
Shortcodes:b:
NameNEGATIVE SQUARED LATIN CAPITAL LETTER B (CLDR)