I'm testing a working web SPA with Cypress, using cypress-localstorage-commands.

before(() => {
    cy.clearLocalStorageSnapshot();
  });

  afterEach(() => {
    cy.saveLocalStorage();
  });

On the first section of code, inside the first "it" I'm just logging into my system by clicking on the different data fields and accessing the section of the web that I'm interested in.

it('Open Simulations', () => {
      cy.visit('/') //Loads the first page
      cy.get('button[id="onetrust-accept-btn-handler"]').click() //Accepts Cookies
      cy.get('.input-box-main-field.required').type('mockuser') //Type the user
      cy.get('input[type=password]').type('mockpwd{enter}') //Type the password
      cy.get('.spinner').should('not.exist') //waits until loading spinner is gone
      cy.visit('/simulacion/nueva') //opens simulations
      cy.scrollTo('right') //scrolls to simular travel button
      cy.get('.sc-EHOje.fgNeQB').eq(7).click() //Clicks on simular
      cy.get('.spinner').should('not.exist') //waits until loading spinner is gone
    })

After this a screen will appear waiting for data submission, this screen needs 4 different data: Destination, Amount of passengers, Date of arrival, Date of Departure.

it('Fill Simulation', () => {
      
      cy.get('.input-box-main-field').contains('Seleccione un destino de viaje').click()//opens drop down menu
      cy.get('ul>li').eq(0).click()//selects 1st element aka Spain
      cy.get('.input-box-main-field.required').type('2')//Setting pasenger number
      cy.get('.input-box-main-field').eq(3).type(dayjs().format('DD/MM/YYYY'))// settign todays date as return
      cy.get('.main-button-text').contains('CONTINUAR').click()//Continue
      cy.get('.spinner').should('not.exist')
    })

After this, the app will validate the data fields and then send the API a post request with the data, so an estimate may be returned. When testing this by myself there is no problem, the post request goes through and I get my result back. When doing it through this Cypress code a problem appears, the auth key is missing, so my backend won't allow me to make a post request. I've no idea why this is happening, the auth key is stored on LocalStorage.