The reason why the brontobyte doesn’t appear on either of these two lists is simple: It hasn’t yet been standardized as a unit of measurement for data. But it’s just a matter of time. The yottabyte, like the brontobyte, is also still a purely theoretical quantity of data and has already been standardized. The next theoretical level above the brontobyte could be gegobyte or geopbyte, which would correspond to 1,000 brontobytes or 1030 bytes.
In any case, the dimensions are enormous. In decimal notation, 1 brontobyte is 1,000,000,000,000,000,000,000,000,000 (1027) bytes. In binary notation, 1 “brobibyte” (not standardized, yet) is 1,237,940,039,285,380,274,899,124,224 (290) byte.
The biggest non-theoretical quantity of data is currently the zettabyte. In 2016, the amount of data traffic worldwide exceeded 1 zettabyte, bringing us into the zettabyte era. 1 brontobyte is equivalent to 1,000,000 zettabytes. The brontobyte era is thus still a way away.