For me the hardest part of the first question is understanding the acronyms. I think MoM is month on month. But MAU, no idea.
The purpose was to make the questions more realistic, since at least in my experience in data analyst interviews the questions are asked in the context of actual business or product situations ... like company leaders, PMs, or others wanting to understand trends in MAU.
Thanks for sharing, I found it very insightful.