It apparently is a very small galaxy with astronomers making this observation:

GN-z11 is 25 times smaller than the Milky Way and has just one percent of the mass of stars our galaxy has

And we are not even that big in the Milky Way.  Stay tuned for more updates on this find.

And here is a related video on the previous record holder with some info on the redshift technique:

One is the galaxy’s redshift, a result of the Doppler effect. Redshift is used to measure the distance, and thus the age, of a galaxy. Instead of a marked drop in sound, as happens with a passing siren, light is stretched and appears redder the farther away any given galaxy is.

Second, EGS8p7 has a visible Lyman-alpha line, a signature of hydrogen gas heated by ultraviolet radiation pouring out of stars in their infancy. This shouldn’t have been possible at the galaxy’s redshift—measured at 8.68—because typically such radiation is absorbed.

Do you think they will break the record again within the next couple of years?

thanks to iflscience.com for the great info