unicorn/prefer-array-flat-map Perf 
What it does 
Prefers the use of .flatMap() when map().flat() are used together.
Why is this bad? 
It is slightly more efficient to use .flatMap(…) instead of .map(…).flat().
Examples 
Examples of incorrect code for this rule:
javascript
const bar = [1, 2, 3].map(i => [i]).flat();Examples of correct code for this rule:
javascript
const bar = [1, 2, 3].flatMap(i => [i]);How to use 
To enable this rule in the CLI or using the config file, you can use:
bash
oxlint --deny unicorn/prefer-array-flat-mapjson
{
  "rules": {
    "unicorn/prefer-array-flat-map": "error"
  }
}