Rekognition get_text_detection not returning Timestamp with milliseconds precision

When submitting a video to Rekognition, get_text_detection is always returning Timestamp with seconds precision instead of milliseconds. For example:

text_detection: {'Timestamp': 4000, 'TextDetection': {'DetectedText': 'ITV Lunchtime News', 'Type': 'LINE', 'Id': 0, 'Confidence': 99.68327331542969, 'Geometry': {'BoundingBox': {'Width': 0.1505126953125, 'Height': 0.033203125, 'Left': 0.35760498046875, 'Top': 0.0947265625}, 'Polygon': [{'X': 0.35760498046875, 'Y': 0.0947265625}, {'X': 0.50811767578125, 'Y': 0.0947265625}, {'X': 0.50811767578125, 'Y': 0.1279296875}, {'X': 0.35760498046875, 'Y': 0.1279296875}]}}}

Code snippets:

response = self.rekognition.start_text_detection(
            Video=self.param_video,
            NotificationChannel=self.param_channel,
            JobTag=self.job_tag,
            Filters=self.param_filters,
        )
        self.job_id = response["JobId"]

while not finished:
            response = self.rekognition.get_text_detection(
                JobId=self.job_id, MaxResults=max_results, NextToken=pagination_token
            )

            for text_detection in response["TextDetections"]:
                print(f'text_detection: {text_detection}')
            if "NextToken" in response:
                pagination_token = response["NextToken"]
            else:
                finished = True

Looks like a bug to me. But it's weird that I didn't find anyone reporting it before. So am I doing something wrong?