Vercel now supports pnpm v7. For deployments with a pnpm-lock.yaml file with version: 5.4, Vercel will automatically use pnpm v7 for install and build commands.
To upgrade your project to pnpm v7, run pnpm install -g pnpm@7 locally and then re-run pnpm install.After updating, create a new deployment!
Check out the documentation as well.