PROBLEM:
Quickbooks online links are blocked by URL Defense.
ISSUE:
The problem is quickbooks has URLs that are longer than 2048 characters which violates http RFCs.
This also breaks the URL Defense encoding and decoding.
WORKAROUND:
Add intuit.com to your URL Defense Exceptions:
This won't help for old emails but should prevent the links from breaking on new emails.
You probably want to open a ticket with intuit.com because this is not a new issue, they encode just way too much data in the URL. There's other ways to write webapps that don't require encoding a massive amount of data and parameters in the links themselves.