Buffer not recognized in TypeScript with Playwright and module: "nodenext"

I am using TypeScript 5+ with Playwright and module: "nodenext" in my tsconfig.json:

{
  // Visit https://aka.ms/tsconfig to read more about this file
  "compilerOptions": {
    // File Layout
    // "rootDir": "./src",
    // "outDir": "./dist",

    // Environment Settings
    // See also https://aka.ms/tsconfig/module
    "module": "nodenext",
    "target": "esnext",
    "types": ["@playwright/test", "node"],

    // For nodejs:
    "lib": ["esnext"],
    "moduleResolution": "nodenext",
    // "types": ["node"],
    // and npm install -D @types/node

    // Other Outputs
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,

    // Stricter Typechecking Options
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": false,

    // Style Options
    // "noImplicitReturns": true,
    // "noImplicitOverride": true,
    // "noUnusedLocals": true,
    // "noUnusedParameters": true,
    // "noFallthroughCasesInSwitch": true,
    // "noPropertyAccessFromIndexSignature": true,

    // Recommended Options
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,
  },
  "include": ["tests/**/*.ts", 
              "playwright.config.ts", 
              "tests-examples/demo-todo-app.spec.ts", 
              "tests/example.spec.ts"]
}

I installed the Node type definitions & Playwright:

npm install --save-dev @types/node @playwright/test typescript

package.json:

{
  "name": "my-project",
  "version": "1.0.0",
  "main": "index.js",
  "type": "module",
  "scripts": {},
  "keywords": [],
  "author": "",
  "license": "ISC",
  "description": "",
  "devDependencies": {
    "@playwright/test": "^1.56.1",
    "@types/node": "^24.10.1",
    "typescript": "^5.9.3"
  }
}

Test file:

import {test, expect} from '@playwright/test';

test('File Upload', async ({page}) => {

    await page.goto('https://practice.expandtesting.com/upload');
    await page.locator('input#fileInput').setInputFiles({
        name: 'testfile.txt',
        mimeType: 'text/plan',
        buffer: Buffer.from('Sample test')
    });
    await page.locator('button#fileSubmit').click();
    await page.waitForTimeout(3000);
})

VS Code shows 'Cannot find name "Buffer"' and does not suggest Buffer in IntelliSense. Playwright test runs fine, so this seems like a TypeScript/IDE issue.

I have tried:

1. Restarting TypeScript server in VS Code.
2. Ensuring the test file is a module.
3. Including "types": ["node"] & "lib": ["esnext"] in tsconfig.json.
4. Installing @types/node locally.

Why does VS Code still show Cannot find name "Buffer" and not suggest in IntelliSense, even though my test runs fine?