Pass a Query Builder to `whereIn` (or `whereExists`) to Reduce Memory & Queries

Rather than pulling IDs into PHP and passing them as a large array You can push the filtering fully into SQL by passing a query builder directly

Benefits:
- The SQL engine handles filtering in one go.
- No PHP-level array of IDs reduces memory and bandwidth.
- Cleaner code without intermediate variables.

Why it Matters
- If you're doing .pluck('id'), you're pulling all matching IDs into PHP and then pushing them back to SQL inefficient and unnecessarily verbose.
- Piping the subquery directly keeps everything in SQL, which is both faster and cleaner.