Possible reasons for unstable PHPUnit test behavior?

Question

PHP

The behavior of the test is shown in the video at the link , just watch 30 seconds to see everything:

1. run the test in normal mode - the test fails.
   
2. set a breakpoint and run the test with debugging - the test passes.
   
3. run the test in normal mode - the test passes.
   

what's the point?
If you want to deploy the code locally, then the link to the repository , see the branch feature/add-integration-tests

Answer 1

If I understand correctly, there is api, somewhere there is a jamb with a response code.
Well, this version of php-unit caught my eye