Excluding customers from seeing Meta Ads

Hi,

I have started to advertise our services from our website on Meta. I have installed the pixel on SQSP and confirmed it is working correctly. One of the things that I would like to do is ensure that people who have purchased from our website are not shown the ads again for a particular campaign. I am unable to select a web url, I.E. thank you page or other to exclude in the adset configuration as I believe that the thank you pages on SQSP are created dynamically after a purchase. Is my understanding correct and if so is there another way to prevent the ad being displayed again to people who have recently purchased from our website?

Tia

Ian