I have recently noticed the Shopify's conversion tracking is sending conversion value in customer local currency.
Specifically, our shop currency is HKD and same as our Google Ads setting. However, the Shopify's code is sending user's order value in USD when user is paying by USD.
Therefore, if a user is paying 200 USD, then what we get from Google Ads is $200 HKD. Which really affect our Google Ads performance. Because I make ROAS incorrect and Google's algorithm is hard to learn from our conversion value.
All Google Ads tracking scripts publicly currently depend on you defining the currency or altering the conversion value to work with commas and decimals. When your store sells in multiple currencies as you allow users to buy in your non-primary currency, things get messy. Shopify introduced presentment currencies last year which changes how such things are done.
Our agency has a new Google Ads tracking script that handles the currency and formatting for everything without complex tweaks to make it work. I haven't made it public yet but plan on updating our Google Ads tracking guide for Shopify, this week. So check back there soon and you'll have a foolproof solution (for all currencies) outside of a patchy answer that addresses just one currency.
Confirming the guide has been updated with a Google Ads tracking solution that works effortlessly for any currency.