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=5.5.4&fileType=.ts&code=KYDwDg9gTgLgBAMwK4DsDGMCWEVxsAZxgB4AVOUfFAEwLiKkxQHMA%2BACgFtgYALCagC44pAJTCGTZnADeAWABQcOGhxE4AQyjM6AXjgByA5rqkA3IuVQeSKLm58BcANSbtBCwoC%2BQA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0ipWsRFCAtonyJoqDJCXQO0SODABfELqA&tsconfig=N4XyA&tokens=false

Repro Code

export function test<T extends string>(method: T): string {
  const args = '' as T;
  return method + args;
}

ESLint Config

{
  "rules": {
    "@typescript-eslint/no-unnecessary-type-parameters": "error"
  }
}

tsconfig

{}

Expected Result

No Error

Actual Result

Type parameter T is used only once in the function signature.eslint@typescript-eslint/no-unnecessary-type-parameters

Additional Info

Original Code: https://github.com/faker-js/faker/blob/cc7715bebded681655b95f5afc368cb250a2eadf/test/support/seeded-runs.ts#L172-L192

The error was first observed in v8.1.0 it does not appear in 7.18.0

The rule seems to ignore any usage of the type inside the actual implementation.