The passenger side wiper blade on my 2010 Honda Accord makes a slapping sound when the wipers are running. This started shortly after my wife had a new blade was installed at Auto Zone but she didn’t notice it for a couple of weeks because it hadn’t rained. I can’t find anything structurally wrong with the blade or arm but I’m not an expert but I’m also not a neophyte.
Not all wiper blades are equal. You could try a different brand. It is possible AZ used the wrong adapter. Or, if the blade is contacting anything other than the windshield, they installed the wrong size blade.