It’s supposed to say “Mbit” or “Mb”. Capital B infers bytes. Incorrect capitalization is one of the most common mistakes when using the metric system. It may be popular but it becomes a problem when 1 B = 8 b, or when 1 MJ = 10⁹ mJ. By the way, common ad-hoc abbreviations like “kbps” as opposed to “kb/s” or “PSI” instead of “lbf/in²” also grind my gears, luckily most such mistakes only occur in imperial units.