Coding overall was easy. The system design didn't requiring any scaling but I struggled a bit with the specific tech to use. In the case study I found the issue but could not propose a quick fix that involved using a reverse proxy. I think these last two interviews were my weakest and likely lead to a rejection

Phone Interview problem: https://leetcode.com/problems/longest-consecutive-sequence/
Onsite coding problem: https://leetcode.com/problems/longest-substring-without-repeating-characters/