What is happening during API validation?

I generated an API with one request path from an OAS and generated a Collection as a Test Suite from that API.
Can I somehow see what exactly happens when I ‘Click to validate’ in the ‘Test’-tab of the API?

In the beginning there was one issue in the response because the content type of the ‘default’ response was different compared to the API definition. I applied the proposed change to my collection. Now there is a green check mark after validation.

But I doubt that the request is actually sent successfully and that the 200 response schema is checked. Instead Postman seems to be just checking the defined default response for the request path. Maybe there is some error when the request is sent.

I added a pre-request-script in the collection for authorization and can submit the request manually without any problem.

So how can I analyze and understand what is happening during validation and what Postman is validating?
Is my assumption actually correct that Postman submits all requests in the collection and validates the responses?