"What is inside?"

Translation: 里面有什么？

[The_Tams]

什么在里面？

[DennisZhao2]

里面 is pronounced really strangely here

[pjtpjt]

If you hover over "is" it will never offer "有".

[MxWldm]

Thats because the sentence roughly translates as: "Inside have what?" To my understanding

[FrankLobo22]

里面是什么？

[Maximilien369]

That is kind of a direct English translation: "Inside is what? (What is inside?)" just the order is changed.
But in Chinese it is the presence of something or the state of having something: so we use only “有” or “在” to describe the situation.