The Jam is part of the Gamedev.js community which started in 2013 with local meetups, and then had workshops/hackathons, newsletter, and much more. It's a brand, and won't be changed, but maybe a little background will clear things for you.
The first Jam was organized in 2020, but there's older event I'm organizing - js13kGames competition, the first edition was held in 2012. This is a difficult and challenging compo where you have to squeeze your entry into a 13 kilobyte zip package, which not even experienced JavaScript developers can do well. That's why the idea for something more open, without any limitations, and so "anything that works on the web fits" in Gamedev.js Jam, even if you exported from Unity and never even seen JavaScript.
Still, the core of the whole thing is JavaScript, and we promote JavaScript games, it's just that anyonoe can participate in the hope of convincing those who use Unity export to see there are really cool games made with engines like Phaser which works way better and faster on the web.
