This is because Qorvo SiC FETs have a very low Cgd, so they tend to turn off very quickly and also have very low turn-off losses. So with an Rg,off of about 20 Ω, you can slow the turn-off of the FET down to a dv/dt of about 80 V/ns, which is still fairly fast and gives very low turn-off losses .

So basically, with an Rg,off of 20 Ω, you can achieve turn-off losses comparable to or better than conventional SiC MOSFETs.