JS is a good language to learn… if you are in Belgium. QA’s often go for Cypress, Playwright these days. BUT that doesn’t mean they do it in your country.
Pretty sure JS isn’t a lost-skill-set since you’ll highly likely touch upon these frameworks also. Postman also uses JS.
If you plan not to work in QA… and want to move towards the developer-side Well then you’re going to have to learn a bit more Probably C#/.NET which are highly demanded here in Belgium. (Doesn’t mean they are in high demand in your region)
This also doesn’t mean you don’t need JS, because then you’ll probably build a website and you’ll probably be in touch with some JS.
So either way JS isn’t a bad option, until you figure out what you really want and what your environment is demanding, I would probably still focus on JS and ‘master’ it before moving to something else.