GA4 Integration with High Sessions and Low Conversion

[JonasO]

Hi,

We have move over complete to GA4 and installed the Google Youtube channel app. A few days in we can see that our ads (Performance Max) runs out of budget completely after a few hours with high peaks in sessions and almost no conversions/sales. Our ads has been stable over 6 months with around 20k impressions. Now we have 80k impression after 3-4 hours with no sales at all. 

We have not adjusted anything in our ads strategy. 

What can cause this effects?

Appreciate your feedback,