Google Ads tag will only count Google Ads conversions. Use Google Analytics and look at the multichannel funnel reports to see how they attributed. However, you still want to add the Google Ads tag and check "include in conversion" column, specifically if you are using automated bidding strategies. The reason being is because those strategies ( assuming conversion related) take into account the conversion column when making adjustments. Google ads will have a different conversion total than Google Analytics because of the default attribution model.