What problem does this feature solve?

On the old browser (like Safari on iOS < 13.4, IE 11...), the Optional Chaining will break the Vue App. We're running VueApp with Standalone Script (Not SPA), so we don't have any transpiler tool to convert Optional Changing in the template (Backend renders) to ES5 syntax

What does the proposed API look like?

Should not break the VueApp. Does have any options for us to solve this issue?

Which script do you specifically use? We already transformed all new syntaxes into es2015. See https://unpkg.com/browse/vue@3.3.4/dist/vue.global.js