DDD thoughts - persistence models vs domain models vs application layer models?

[hansmbakker]

I see Clean Architecture is an important part of this repository. I'm figuring out how to best approach that and what to put where.

I see an application layer? version of the TodoItem model in the Web API project.
Also I see you have your Core (domain model) project where you have your entities, and it seems that they are stored directly in CosmosDb. I understand it is possible to put a nested object in CosmosDb directly, but I was wondering whether could explain a bit about the thoughts (pro/con) of storing your domain model objects directly in the database?

Or more generally: when do you make the separation, and when not? (I personally would say "where you want to be independent from schema changes", but would like to discuss thoughts)

I found a relevant discussion on this topic on Reddit: https://www.reddit.com/r/csharp/comments/ewv7qf/ddd_converting_between_domain_and_storage_model/