AWS Timestream: Connection errors

Question

We're running into really weird errors with AWS Timestream recently. Trying to write the value ${ into the DB seem to lead to a connection error.

import boto3
client = boto3.client("timestream-write")
# 1:
client.write_records(DatabaseName="db",TableName="table",
        Records=[{'MeasureName': 't', 'MeasureValue': '${', 'MeasureValueType': 'VARCHAR'}],
        CommonAttributes={'Dimensions': [{'Name': 'test', 'Value': 'asdf'}], 'Time': '1648179254162'})
# 2: 
client.write_records(DatabaseName="db",TableName="table",
        Records=[{'MeasureName': 't', 'MeasureValue': 'asdf', 'MeasureValueType': 'VARCHAR'}],
        CommonAttributes={'Dimensions': [{'Name': 'test', 'Value': '${'}], 'Time': '1648179254162'})
# 3: 
client.write_records(DatabaseName="db",TableName="table",
        Records=[{'MeasureName': 't', 'MeasureValue': 'asdf', 'MeasureValueType': 'VARCHAR'}],
        CommonAttributes={'Dimensions': [{'Name': 'test', 'Value': '$asdf'}], 'Time': '1648179254162'})

#1 & #2 result in botocore.exceptions.ConnectionClosedError: Connection was closed before we received a valid response from endpoint URL: "https://ingest-cell1.timestream.eu-west-1.amazonaws.com".
#3 works fine.

Is this a known thing? Are we doing something wrong?