Venatus technology is using GAM scripts when loading its wrapper. Sometimes it happens that publishers had their own GPT tags installed previously.
From the first look, it might seem that all calls to Google are commented out but usually, the site is still loading gpt.js and initializing GPT tags outside of our ad stack.
The problem is that publisher code could be reinitializing GPT after our stack has already loaded and rendered the first ad, causing the flash and a new ad load in the process.
If you notice the ad is flashing and then the new ad is refreshed instantly please check if all your Google scripts are removed.
If still doubting please reach out to our team.