I'm guessing the version of nwjs is bundled with RPG Maker MV, and that you need to update it by updating RPG Maker MV itself...but it hasn't received any new updates for a few years.
But doing some more research, I found this post: https://itch.io/blog/484532/how-to-update-nwjs-in-rpg-maker-mv-for-rpg-devs
> Fortunately, RPG Maker MV uses an unmodified copy of NW.js as its runtime for desktop deployment, which means it’s pretty easy to update it manually! The process isn’t really different between development OS, so I’ll go through it target by target.
The process is essentially the same thing I did on my end, with a few more steps. The post recommends deleting files, but all I did was copy some files over and replace older files with the same name and I had no issues playing the entire game.
Also, disclaimer that I have no idea what I'm doing :) I haven't touched RPG Maker since XP, and I never ended up making a game with it, lol.