Excel automatically adds quotation marks at output of CONCATENATE function

This issues appears now and then especially when the input has certain quote marks. It's partially because of the feature of CONCATENATE function, i.e, remove all the quote marks when doing concatenation?

Resetting the format won't work.

Since this problem appears 'unpredictably',

A not-so-elegant solution is: Everytime I use this concatenate function, I duplicate my previous excel sheet that didn't automatically add quote marks, and make modifications on top of it. It worked.

Hopefully someone will find a systematic solution to this.