I’ve taken a full backup of your site and restored it on my local PC. After removing the unpublished pages from the SP Page Builder section (not just moving them to trash), I ran the indexing process, which completed successfully without any errors. Additionally, I enabled the Smart Search Tags plugin to support proper indexing.
Please try the same on your site:
•   Ensure unpublished pages are permanently deleted, not just trashed, as items in the trash may still interfere with indexing.
•   Then, rerun the indexing.
If the issue still persists, I recommend the following steps:
- Take a fresh backup using Akeeba Backup.
- Restore the site locally on your PC.
- Delete all unpublished pages from SP Page Builder.
- Run the indexing process again and monitor the result.
Following these steps will help identify whether the issue is due to the hosting environment—such as server caching or blocked requests.
Let me know how it goes.
Thanks,