I think is the reason that the advertiser itself included chinese traffic for their ads to be display, somemore, will it be possible that your PC set a google's behavior cookie? which mean google ads bot recognize that your 'behavior' matched with the advertiser's ads? Coz amazone does set a cookie on our PC to keep track our behavior
...they usually answer quick enough. Unfortunately it's usually some cookie cutter response that raises more questions than actually answering them. NEhoo, please let the curious minds at DP know the results