Facing Theme Issues

[Faad]

Recently bought atom theme https://themes.shopify.com/themes/atom/styles/relativity

After customizing and publishing the theme, I observed that certain products were not loading properly and were displaying blank pages, while others were loading fine. Additionally, some products were not opening in the default theme template as expected on the backend. This issue seems to be quite unusual and requires further investigation to pinpoint the exact cause. 

I've contacted the theme owners as well but they are not responding. Attaching Video for better understanding.

https://drive.google.com/file/d/1y50xvrShJTsTB7JWafkRDYt_gEiMlnQ6/view?usp=drive_link

[AK81]

The performance of this theme appears to be suboptimal and shows signs of instability, lag, and slowness. Improvements are needed to provide users with a smoother and more responsive experience. The developer needs to address these issues to improve the overall quality and usability of the theme.

[Faad]

Can you help me figure out the issue?