Microsoft Software Developer interview questions

Online test consisted of three questions to be solved in 1.5 hours. Trim a BST, pattern matching and non repeating character. 68 students were shortlisted out of 250 and there was another test conducted on paper. We were asked to solve 2 DP problems: number of deletions required in an array to make it sorted in increasing order and word break problem. There was a group discussion round after this where we were given a problem and we had to come up with plausible approaches to solve the problem as a part of the discussion. After this round there were 3 rounds of technical interviews and 1 HR interview.

Recruiter invited me to apply for a role and do an Online Technical Screen and said I could use any language I like. The questions were straightforward and I completed them in Python easily and included the description of the thought process. I soon got a rejection -- asked why and the feedback was they don't want built-in methods (which was not mentioned in the question) and the array was not initialized (it was -- and it ran fine when I tested locally). My guess is the grader was reviewing the answers with a mindset from C/C++/Java and my Python solutions got penalized under their mindset. As someone who passed multiple rounds of Facebook/Airbnb whiteboard algorithm grilling, I have to say this feels kinda absurd.