What shader languages ​​are currently relevant? And in unity?

Question

Shaders

Hello! I did my little crafts on CG in Unity and did not think about why CG. I was just advised so (??). Now I climbed on Wikipedia and saw the following: "Since 2012, Cg is outdated."
Well, what language is now then more or less relevant and universal? Do I understand correctly that a shader written in the wrong language can destroy all cross-platform? Those. Works fine on Windows, but not on mobile?