Hi Caesars,
Greetings from Syncfusion support.
We checked the reported requirement. We would like to inform you that, while scrolling the page in the browser, the popup position will be change based on the browser. So if you close and again open the popup, the position will be updated related to the input element. Please check this case and if still issue persists, Kindly share the details about in which case you are facing the issue.
Regards,
Sevvandhi N