Just finished the loop last week so this is fresh. Posting because I couldn't find a recent write-up that wasn't 2022 Glassdoor and basically useless.
The online assessment comes before any recruiter call, which surprised me. It's HackerRank-hosted, timed at 90 minutes for two problems. Mine were: A graph traversal problem (BFS, find shortest path given constraints). Classic medium on leetcode, maybe low-medium-hard with the constraint twist. A string parsing problem that looked easy but had edge cases around empty inputs and unicode. Spent way too long on that second one.
Difficulty: I'd call it solid medium. Not the "you need to know obscure DP" level you get at Google, but not the easy warm-up stuff some companies use either. If you can consistently solve LC medium in 30-35 minutes you're probably fine.
Language: you can pick whatever. I used Python. Didn't hear of anyone getting dinged for language choice.
Timing: heard back from the recruiter about 5 business days after submission. No automated result before that.
One thing I did NOT expect: they apparently look at code quality, not just passing test cases. My recruiter mentioned during the debrief that my variable naming was good and the solution was readable. So don't just brute-force to pass, write like someone's going to read it. Because they apparently do.
Post your own below if you've done the Cloudflare OA recently. Curious if the format has shifted at all.