Comically quaint (Merriam – Webster)
Mildly teasing or mocking. (Merriam – Webster)
Expressive of puzzlement, curiosity, or disbelief. (Merriam – Webster)
Seeming to ask a question without saying anything. (Cambridge Dictionary)
Odd, queer, or comical. (Dictionary.com)
Questioning or puzzled. (Dictionary.com)
If you give someone a quizzical look or smile, you look at them in a way that shows that you are surprised or amused by their behaviour. (Collins Dictionary).
The quizzical story behind a quizzical word.