Are environment variables safe to use?

I am building a VITE react app that I will be deploying using Vercel or Netlify using their environment variables. Would it be secure to pass my ID's in the vercel's env. Wouldn't that make the ID's accessible in the frontend code?

TL;DR

Developers are concerned about the safety of using environment variables with VITE, React, Vercel, and Netlify. They worry that passing IDs in Vercel's env might make them accessible in frontend code.