### Apache Airflow version

2.1.3 (latest released)

### Operating System

Debian Buster

### Versions of Apache Airflow Providers

_No response_

### Deployment

Managed Services (Astronomer, Composer, MWAA etc.)

### Deployment details

Running `quay.io/astronomer/ap-airflow:2.1.3-buster` Docker image

### What happened

In the task attributes view of a BashOperator, the `template_ext` row doesn't show any value, while I would expect to see `('.sh', '.bash')`.

![image](https://user-images.githubusercontent.com/6249654/131467817-8620f68d-0f3d-491d-ad38-cbf5b91cdcb3.png)


### What you expected to happen

Expect to see correct `template_ext` value

### How to reproduce

Run a BashOperator and browse to Instance Details --> scroll down to `template_ext` row

### Anything else

Spent a little time trying to figure out what could be the reason, but haven't found the problem yet. Therefore created issue to track.

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

airflow/serialization/serialized_objects.py
"""Deserializes an operator from a JSON object."""
        op = SerializedBaseOperator(task_id=encoded_op['task_id'])
        if "label" not in encoded_op:
            
            encoded_op["label"] = encoded_op["task_id"]
        
        op_extra_links_from_plugin = {}
        
        if cls._load_operator_extra_links:
            from airflow import plugins_manager
            plugins_manager.initialize_extra_operators_links_plugins()
            if plugins_manager.operator_extra_links is None:
                raise AirflowException("Can not load plugins")
            for ope in plugins_manager.operator_extra_links:
                for operator in ope.operators:
                    if (
                        operator.__name__ == encoded_op["_task_type"]
                        and operator.__module__ == encoded_op["_task_module"]
                    ):
                        op_extra_links_from_plugin.update({ope.name: ope})
            
            
            
            
            if op_extra_links_from_plugin and "_operator_extra_links" not in encoded_op:
                setattr(op, "operator_extra_links", list(op_extra_links_from_plugin.values()))
        for k, v in encoded_op.items():
            if k == "_downstream_task_ids":