Teams lose weeks to an SSO login test that cannot be made to work. Several engineers try. Someone suggests the tests are badly written.
Usually nothing is badly written. They are fighting the architecture, and nobody has explained it to them.
Senior work with any tool starts here: you should be able to predict what the tool cannot do, before you try it. For Cypress that prediction comes from one fact.
Cypress runs inside the browser, in the same window as your application.
Everything else follows. Read the consequences slowly, because each one explains a whole category of problem you will meet.