Meta New Grad Security Engineer Interview Experience

One of the worst onsite interview experiences.

I was selected for a New Grad Product Security Engineer interview. The recruiter reached out and asked to schedule a meeting. Rescheduled it for two times and finally scheduled a screening round of 60 mins with 50% coding and 50% security related topic. One day before the screening again rescheduled it for next week. Finally appeared for the screening round. It was a good experience. The interviewer was really helpful and cooperative.
Question asked: Valid Palindrome and lot of scenario based web security questions related to CSRF, XSS, Password Hashing, cookies, etc.

Qualified and scheduled onsite round spanning for two days in two consecutive weeks:
Day 1: Security Code Review (Web In Domain), Security Systems Design
Day 2 : Coding, Behavioral.

After couple of days, re-scheduled the Systems Design round to a third week. Now I am having onsite spanning for three weeks :)
The security code review was a new kind of round for a new grad role. So I asked for the programming language and frameworks that I am supposed to encounter. Repeatedly, the recruiter provided only coding (Data Structure Algo) resources and a generic interview prep guide with no mention of languages and frameworks what so ever. Obviously the recruiter had zero idea about the round.

I appeared for the code review round today and the interviewer posted a codebase written in PHP :) I have zero knowledge of PHP and it was never mentioned on my resume or anywhere else on my profile. Also it was written that the code review round is (Web in domain round) but guess what! not a single line of JavaScript in a web security interview :) Provided a vulnerable server side codebase in PHP. Clearly mentioned to the interviewer that I do not have experience in PHP still he insisted me to review the code. Did my best but how can a person without the knowledge of a programming language review a codebase!! It's like asking someone who knows English to review an essay written in Japanese!

How can these so called FAANG companies (with tons of employee) are not programming language agnostic!!! How can a New Grad Role consist of some "Code Review" round in an absurdly weird Programming Language (PHP)?? Why have they even selected me for this role if they need some veteran PHP coder?

FYI: I have both security and software engineering internship experience and worked with several programming languages (Python, Java, JavaScript, Ruby) and frameworks (Flask, Angular, Spring Boot, Rails) both academically and during my internships.

EDIT: I appeared for the onsite coding and behavioral rounds today. Questions asked:

1. 3 Sum: Only had to return boolean if triplet found not the list of triplets
2. Make the shell script command cd: A variation of Simplify Path but insted of starting from root, the function will take another argument for present working directory. Example: cd(pwd, path) so if pwd = '/home/user' and path = '../document' then answer will be /home/document path can be absolute as well as relative if absoulte then we need to ignore pwd. Needed to solve both of them optimally.

Behavioral was pretty standard as well: Conflict resolution, best team, worst team, lessons learned, etc.

EDIT: I appeared for the Security Systems Design Round. Question Asked:
Given a UI of an online coding exam platform, I was asked to desing it keeping security in mind (traditional systems design requirements like Scalability, Maintainability, etc was out of the scope).
As expected, the interviewer was extremely rude and did not even answer the clarifying questions. I asked if the candidate will require to sign in to a career portal or will they receive the link via email, he answered "You tell me, you are the architect here". Then I asked if he want me to focus on the client side (JS) or the backend side, as security can be implemented in both, he said "you decide whatever you think is more important." I could not even clarify the functional and non functional requirements :)

EDIT; I got rejected (As Expected). I hope they find a E4 level engineer for a New Grad Role :)