I can't figure out why my queries are returning empty

I am using a serverless + atlas API arquitecture.

This has worked for the last two years and all of a sudden my queries return empy.

This is in my handler:

module.exports.getByString = (event, context, callback) => {
  context.callbackWaitsForEmptyEventLoop = false;

  connectToDatabase()
    .then(() => {
      var nameRegex = new RegExp(event.pathParameters.query);
      console.log(event.pathParameters.query);

      Cosmetic.find({product_name: {$regex: nameRegex, $options: 'iu'}}).collation({locale: 'fr', strength: 2})
        .then(notes => callback(null, {
          statusCode: 200,
          body: JSON.stringify(notes)
        }))
        .catch(err => callback(null, {
          statusCode: err.statusCode || 500,
          headers: { 'Content-Type': 'text/plain' },
          body: 'Could not fetch the notes.'
        }))
    });
};

If I search directly on Atlas it works:

When I test it on AWS Lambda it also returns the same:
{
“statusCode”: 200,
“body”: “
}

for the JSON input:
{
“pathParameters”: {
“query”: “Mazz”
}
}

Does anyone know what is happening?