Vector Incorrectly Assigns Some Logs with a Level of "default"

Description of problem:

When using Vector as the logging collector, some log formats correctly contain the level, but are still getting assigned a level of "default" by Vector.  

Version-Release number of selected component (if applicable):

cluster-logging v5.6.6

How reproducible:

This happens consistently with logs from most, if not all, of the pods from the Advanced Cluster Management operator. There may be other operator logs outside of ACM this impacts as well.

Steps to Reproduce:

1. Install ACM on a three-node cluster
2. Install cluster-logging v5.6.6 and the elasticsearch-operator on the cluster
3. Configure the ClusterLogForwarder to send logs to the default Elastic using Vector
4. Log into the local Kibana Discover dashboard and filter for level: "default" and kubernetes.namespace_name: "open-cluster-management-agent-addon"

Actual results:

Search results contain several entries labeled as level: "default", but the message clearly has a level of "info" or similar.

Expected results:

Search results contain entries that legitimately do not have a log level in the message.

Additional info:

Please see the attached for an example log file