Testing wordpress site with Cypress

I am trying to test my own wordpress plugin with Cypress.

I've encountered the following issue: if I add items to the cart with the built-in "Add to cart" button and navigate to the cart, it is empty.

If I try the same scenario manually with the cypress chrome browser beside the tests, the same thing happens.

Code:

it("puts in the cart", () => {
    cy.getChatbotIframe()
    .find("[data-cy=coupon-code]")
    .invoke("text")
    .then((text) => {
      cy.getChatbotIframe().find("[data-cy=go-to-cart-button]").click();
      cy.get("[data-cy=coupon-code]").contains(text);
    });
});

The getChatbotIframe command:

Cypress.Commands.add("getChatbotIframe", () => {
  return cy
    .get("[data-cy=alkubot-chat-iframe]", { log: false })
    .its("0.contentDocument.body", { log: false })
    .should("not.be.empty")
    .then((body) => cy.wrap(body, { log: false }));
});