Originally thought to be a brown dwarf,, it has a mean temperature of 1,500 f, and a measured magnetic field about 4 million times as strong as the earth's magnetic field. .
There's nothing there that empirically stops it from "being" a brown dwarf in the sense of definition. It's simply at the lower edge of brown dwarf possibilities, just about at the point where it could fuse deuterium. Due to its mass of 12.7+-1.0 M_Jupiter (below the IAU-standardized rule of thumb of 13 M_Jupiter, although that's contested and often stated as "12-13") it was relegated from a Class T2.5 brown dwarf to an "object of planetary mass" in 2017.
The temperature (1089K) is based on its bolometric luminosity (and standard models deriving it from that), and is entirely in line with a deuterium-fusing brown dwarf. For scale: If one derives a temperature proportionality to pressure, i.e. to r³ then it's only about 30% hotter than Jupiter.
There are some non-star-system (free-floating) objects of similar dimensions close to us with lower temperature, such as UGPS J072227.51−054031.2 or WISE J085510.83−071442.5[, but there has overall been relatively little observation spent on such objects.
The magnetic field strength interestingly at 200 times the dipole moment strength of Jupiter is about the same as measured for LSR J1835+3259, another brown dwarf about the same distance from us.
