Dumb question - is 1.12.4 acceptable version for new site deployment?

And how difficult would it be to update to 3.4.0

We have web designers putting together new website for us and I notice via Google Lighthouse that the jquery version 1.12.4 which has been compromised in past (recent article as well). Is it a big deal to go from 1.12.4 to 3.4.0?

I am wondering whether I should ask the web developer to upgrade it. Have them explain it a very least.