Questions with "Even"
I didn't know it was possible to do a question using EVEN. Someone could to explain how it works, please? (Feel free to correct my writing).

I read this on website: "Tipping is arguably the most stressful part of eating out (besides actually choosing a restaurant). There are no set rules to tell you exactly how much to tip your server, so you’re left guessing how to convert service quality into cash. Plus, figuring out tips for other services, like travel or beauty treatments, is just as confusing. Even more confusing?"

If it is wrong, the correct question should be: Are you even more confusing? I was thinking maybe the writer just shortened it. What do you think?

Question

Questions with "Even"
I didn't know it was possible to do a question using EVEN. Someone could to explain how it works, please? (Feel free to correct my writing).

I read this on website: "Tipping is arguably the most stressful part of eating out (besides actually choosing a restaurant). There are no set rules to tell you exactly how much to tip your server, so you’re left guessing how to convert service quality into cash. Plus, figuring out tips for other services, like travel or beauty treatments, is just as confusing. Even more confusing?"

If it is wrong, the correct question should be: Are you even more confusing? I was thinking maybe the writer just shortened it. What do you think?

Answer

/confussing"is even more confusing" "is just as confusing" are the full structures that can be used, but colloquially the "collocation" "even more confusing" is often used as a Tag thought it means the same. People would know what is meant and be able to mentally insert either of the two other forms if they need clarification in their minds.  A native would know what is meant.

"are you even more confused/confussing is wrong" the writer is saying that this tipping dilemma is confusing, figuring out tips for other services is even more confusing"

Answer

I would suggest. "is just as confusing or maybe even more confusing?"