Evergreen will upgrade its YAML parsing library on Dec 12, 2022 as part of EVG-17291. This upgrade may result in our project YAML (i.e. test/evergreen.yml) being parsed differently and becoming invalid if it relies on using YAML anchors to do a deep merge of nested maps.

We should run the below suggested validate command and make the necessary updates to the test/evergreen.yml file, before the planned Evergreen YAML parsing library upgrade. 

evergreen validate -p <your_project_name> --use_upgraded_yaml <path_to_yaml_file> 

The change will need to be backported to all supported release branches that have an associated Evergreen project running actively.