Quick update. Looks like problem isn't in banner code. This is information what I get from GWD support team. Hope this helps if someone will have the same problem.
After extensively checking your creatives in Firefox and Chrome browsers, we’ve determined that the clickthrough events are firing properly and that the issue seems to be with the GoogleAds API.
Here are the browser versions we tested it on (Mac OS 10.14.5):
Chrome Version 74.0.3729.169
Firefox Version 67.0
And here are our findings for both browsers:
Local preview shows that the exit event (clickthrough) are firing properly on Chrome. Here is what it shows on the Chrome’s built in debugging tools: Exit "Product_0_url" invoked
Likewise, the exit event (clickthrough) are also being invoked properly on Firefox. Built-in debugging console in Firefox also shows a similar result: Exit "Product_0_url" invoked.
We also examined the creative attached on this email thread and confirmed that you already implemented the fix for clickthroughs not working in FireFox, as suggested by my colleague Michael.
With that being said, we’ve determined that the issue is most likely with Google Ads platform and not the actual creative. As much as we would like to troubleshoot this further, the best team to address this issue is Google Ads Support. For further assistance please contact them through this link: Google Ads Support