When I enter the store page, the default picture of theme appears.

Thanks for using Modern Store!

That image isn’t included with the theme and the images don’t normally load in this manner, so it looks like the issue is coming from a plugin on the site.

I’m seeing some strange things right now, like when I copy the image address of one of the product images, it points to a page that looks like this: https://lessthan5pound.com/wp-content/uploads/2020/07/GoogleDrive_SERI-NO-39__DENTAL-FLOSS-2PCS-IN-PACK__IN-STOCK-12__50-GRAM__FIYAT-3__MADE-IN-UK-1536×1536.

I would start by checking if there’s a plugin on your site that is importing your images from Google Drive or another server instead of loading them from your site. You may need to deactivate your plugins and then reactivate them one-by-one until these errors return.