I just did the LinkedIn OA last month and the format is a bit different from what I read in older posts, so figured I'd update the record.
Platform: They use their own internal assessment tool now. It's fine. The code editor syntax highlighting worked. No complaints.
Format: 2 coding problems, 70 minutes combined. No behavioral section in the OA itself. No debugging/fix-the-code sections, pure problem-solving.
Difficulty: I'd call them Leetcode medium and medium-hard. The first problem was a classic sliding window variant, nothing shocking. The second involved trees and had a subtle requirement about ordering that I almost glossed over. I'd say the OA screens for "can you write clean, correct code under time pressure" more than "do you know obscure algorithms."
Test cases: You get public test cases and can run your code. Hidden test cases are revealed after submission. I passed all public but one hidden case failed on the first problem because I had an off-by-one error. Still moved on to the phone screen, so partial credit apparently counts.
Time management: This was my real challenge. I spent way too long trying to optimize the first problem perfectly before moving on. Lesson: get a working solution first, then optimize. They care about correctness more than Big-O theorizing if you're not a senior candidate.
For new grads and early career folks: I think Leetcode mediums done under actual time pressure is the right prep. Not grinding Leetcode hard obsessively. Get comfortable being 80% right and explaining your thinking.
Got the phone screen invite 8 days after the OA. Good luck everyone.