Unable to filter errors

I’m unable to filter errors.

The docs I’ve checked: https://docs.sentry.io/error-reporting/configuration/filtering/?platform=javascript#before-send

The error Json from Sentry:

{
  "event_id": "e808f58c580a42e48fb8160ada3c271d",
  "project": 189513,
  ... 
  "title": "Error: ResizeObserver loop limit exceeded",
}

My code:

        beforeSend(event) {

        if(event.title === 'Error: ResizeObserver loop limit exceeded')
            return null;

        return event;
    }

What I’m doing wrong? Thanks