I think it's worth mentioning annecdotal, but credible, reports that once you get above 10TB, they have been known to contact you to require you reduce your backup size.
Also, noting their speed limits, you may find that you practically never get a complete initial backup.
Despite the increased cost, you may want to consider using Backblaze B2.
If you can reduce your 80TB backup, I recommend you do. For example, if that's literally everything you have, perhaps backup only irreplacable data such as photos and documents.