I'm puzzled at how this so-called a"thing". How this phrase contribute to the overall tone of the text?

Hello. You did not inform the text to which this question is referring, which makes it impossible for it to be answered accurately, however, I or try to help you in the best possible way.

It is only possible to actually know the tone of the text by reading it. However, if we analyze the sentence "I'm puzzled at how this so-called a" thing "" we can infer that it contributes to a tone of curiosity and distrust, since the speaker of this sentence, feels like this in relation to "thing "and displays this feeling to the reader.

not concrete, existing in thought or as an idea but not having a physical or concrete existence