the online test had 4 different problems to solve the first and second easy the third and fourth medium. I submitted the first, second, and forth but the fourth didn't pass all the tests.

Multi-stage process for a fullstack internship (React/Node/TS/REST APIs/databases/clean code). Started with CodeSignal assessment (4 coding exercises), HireVue one-way video (6 behavioral questions), and first live coding (60 mins, collaborative with helpful hints from Senior Engineer). Advanced to second 60-min technical round with Lead Engineer. The provided case study (datasets + fullstack skeletons) was discarded; instead, focused on unrelated CV project and gave vague task to build a mathematical expression parser/evaluator from scratch. No guidance, frequent silence, camera/mic off. Felt dismissive and non-collaborative. Rejected immediately after with no feedback.