is correct that Infrastructure elements implement Domain elements?

[borrown]

I'm not sure if I should avoid using Domain objects into Implementation as you do in the next line:

https://github.com/CodelyTV/php-ddd-example/blob/51ffa79ce54b680a6046857b3cf442fa6e2c014f/src/Backoffice/Courses/Infrastructure/Persistence/ElasticsearchBackofficeCourseRepository.php#L7

I thought only Domain objects and Application objects could instantiate or implement Domain objects. In other words, Infrastructure only needs to know implementation signatures from the application layer where the infrastructure object will be used.