try

Author: dimaMachina

packages/graphiql/cypress/e2e/prettify.cy.ts

@@ -40,7 +40,7 @@ describeOrSkip('GraphiQL Prettify', () => {
       cy.visit(`/?query=${rawQuery}&onPrettifyQuery=true`);
       // Wait diagnostic error
       cy.get('.squiggly-error', { timeout: 10_000 });
-      cy.get('.graphiql-query-editor textarea').type('{shift+ctrl+p}', {
+      cy.get('.graphiql-query-editor .monaco-editor').type('{shift+ctrl+p}', {
         force: true,
       });
       cy.assertHasValues({ query: resultQuery });