Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have searched for related issues and found none that matched my issue.
• I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=6.0.2&fileType=.tsx&code=FASwdgLgpgTgZgQwMZQAQDED2nUG9iqqYCu0MAtpgM4RaYAUAlAFwbYA%2BYxANt8AL7BgcYmCQQQmMKiggIAC1h0A8jAByPbk1Z1U7VF154CqGFAjEY0gLIIFAOhgIwAE0zkmqADyoADPYBWVAB%2BPBIySho6Vk8AXgA%2BA01%2BVFZDbgBuASEkKRpUOGxUWJk5RRgVdU0mLJA4VHoAQkKcdn0W%2B3DYSNpsT0bYkpbGY0IAejHUABEcKndzeXAAc3tsoA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Y6RAM0WloHsalfkwCG8WmQAWo5uii9o-aJHBgAviHVA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eFYDAruuGAL4g9A&tokens=false

Repro Code

interface Foo {
  outermostFoo(): Foo|null
}

function eitherFooOrNull(): Foo | null {
  return Math.random() < 0.5 ? {outermostFoo: () => null} : null;
}

const foo = eitherFooOrNull();
if (!foo || foo.outermostFoo() !== foo) {
  // Do something.
}

ESLint Config

module.exports = {
  parser: "@typescript-eslint/parser",
  rules: {
    "@typescript-eslint/prefer-optional-chain": "error",
  },
};

tsconfig

{
  "compilerOptions": {
    "strict": true
  }
}

Expected Result

No error/fix happening.

Actual Result

The if is re-written

const foo = eitherFooOrNull();
if (foo?.outermostFoo() !== foo) {
  // Do something.
}

This is a true semantic change, because optional chaining coerces the null into an undefined, which means in the case where foo is null, the if changes to undefined !== null. We will no longer take the if branch.

Additional Info

Broken in the upgrade from 8.47.0 to 8.52.0. Upgrading typescript-eslint in the Chrome DevTools code base causes actual test failures due to this rewrite and we had to disable the rule.