ECMAScript modules (ESM): Yes, when you export an object the reference is shared across all usages

esm-object-export-is-a-shared-reference.md

$ node index.mjs
🌞 module-a pre-export { name: 'module-a 🌞', obj: { a: '🇨🇦', b: 'bee', c: 'see' } }
👻 module-b pre-export { name: 'module-b 👻', obj: { a: '🇨🇦', b: '🐝', c: 'see' } }
{
  moduleA: { name: 'module-a 🌞', obj: { a: '🇨🇦', b: '🐝', c: '👀' } },
  moduleB: { name: 'module-b 👻', obj: { a: '🇨🇦', b: '🐝', c: '👀' } },
  moduleObjectExport: { a: '🇨🇦', b: '🐝', c: '👀' }
}

index.js

import moduleA from './module-a.mjs';
import moduleB from './module-b.mjs';
import moduleObjectExport from './module-object-export.mjs';

moduleObjectExport.c = '👀';

console.log({ moduleA, moduleB, moduleObjectExport });

module-a.mjs

import obj from './module-scope-object-export.mjs';

obj.a = '🇨🇦';

const result = {
  name: 'module-a 🌞',
  obj
};

console.log('🌞 module-a pre-export', result);

export default result;

module-b.mjs

import obj from './module-scope-object-export.mjs';

obj.b = '🐝';

const result = {
  name: 'module-b 👻',
  obj
};

console.log('👻 module-b pre-export', result);

export default result;

module-object-export.mjs

export default {
  a: 'eh',
  b: 'bee',
  c: 'see',
};