SharePoint Online is a powerful tool for business, but it lacks the essential ability to restore files once they’ve been removed from the recycle bin. Deleted items stored in these locations are automatically removed after 90 days. Not even your site collection admin will be able to touch them then.
It is a compliance standard in many countries that businesses are required to retain their financial records for 7 years. This is best practice for all businesses, especially accountants, but it also means a lot of data that needs to be accessible somehow from somewhere.
A third party backup tool is the best solution for your compliance and governance needs. Backing up your data is the only way to restore it beyond the recycle bin and will ensure business continuity after natural disasters, service disruptions, or human error. And with your files readily to hand, your business will also achieve compliance.