Why is there a delay before chrome console network request?

Address:

https://developers.google.com...

As shown in the picture:

Question 1: There is a red line underneath the request, that is, there is a gap between the 5th request and the 6th request, that is, there is a gap after the end of the 5th request and before the start of the 6th request. Why?

Question 2: In our project, some requests are synchronous and some are asynchronous. For example, the second and third requests start at the same time. In daily projects, which ones are synchronous and which ones are asynchronous

Thank you very much if you can clear up the confusion

Reply content:

Address:

https://developers.google.com...

As shown in the picture:

Question 1: There is a red line underneath the request, that is, there is a gap between the 5th request and the 6th request, that is, there is a gap after the end of the 5th request and before the start of the 6th request. Why?

Question 2: In our project, some requests are synchronous and some are asynchronous. For example, the second and third requests start at the same time. In daily projects, which ones are synchronous and which ones are asynchronous

Thank you very much if you can clear up the confusion

The browser will block the page when loading js
clickXHR, all requests inside are asynchronous.