See discussion in jsx-eslint/eslint-plugin-react#2882

There are only two cases in this project that we honour parserOptions.ecmaVersion, and both are in scope-manager:

These usages were brought across when I forked eslint-scope.

However in the context of TS scope analysis - the ecmaVersion makes zero sense.
TS will never treat your code as if it's ES5 or lower - it is always (syntactically and semantically) "ESNext".

Whilst other parts of the ecosystem respects them - and they should continue to - our parser and scope analyser should (like TS itself) always treat code as if it is ESNext in terms of language features.