Sorry for the delayed response and inconvenience caused. As per the description above, when converting a PDF to Excel, all columns are merged into one, Is that correct?
Try exporting the PDF file through the URL https://cloud.acrobat.com/exportpdf with your Adobe ID and password on a browser like Chrome, or Firefox, or Safari and see if this brings any difference.
You can also refer and try the suggestions from the following Adobe discussion where the similar issue is answered I need to convert PDF to Excel, however, columns and tabs make many merged cells and many blank colu...
You can also refer to Text is garbled in converted file | ExportPDF
The record shows that you are subscribed to Adobe PDFPack services with the current Adobe ID.
Is it possible to share a sample PDF file with us so that we can try it at our end? To share the file, please use Adobe Send feature, upload the file, share the link to files via private message only, How Do I Send Private Message
For more troubleshooting, you may refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud...
Let us know how it goes and share your findings.