This is another one of those posts so I can remember where some useful information is….
If you are migrating your Azure DevOps Classic Builds and Release to Multi-Stage YAML then an import step is to export all the exiting build, task groups and release as YAML files.
You can do this by hand within the Pipeline UI, with a lot of cut and pasting, but much easier is to use the excellent Yamlizr – Azure DevOps Classic-to-YAML Pipelines CLI from Alex Vincent. A single CLI command exports everything with a Team project into a neat folder structure of template base YAML.
I cannot recommend the tool enough