The report comes courtesy of Making Star Wars, which has learned about a stormtrooper referred to as The Executioner.
It seems odd, then, that Rian Johnson and company would create a character like The Executioner, which potentially could overshadow Phasma yet again.
Another interesting detail included in the rumor is that Finn will go head-to-head with The Executioner, obviously a callback to his short encounter with TR-8R.
After TR-8R was a scene-stealer, the team behind Star Wars: Episode VIII would be hard-pressed to top it.