SeaORM's DatabaseConnection type is not Send, Sync and Clone.
These should be easily added as DatabaseConnection is a wrapper of the Sqlx pool types, which themselves are Send, Sync and Clone.

On the Sqlx Pool documentation:

Pool is Send, Sync and Clone, so it should be created once at the start of your application/daemon/web server/etc. and then shared with all tasks throughout its lifetime.

This is usually needed for many apps, such as an actix server, so it can be sent between threads to aquire new connections.