There sure is in desktop, I ran one today. It is in reports, customers, Unbilled activity or similar
If QBO has it that's where you will find it. Then you can filter for customer or by date.
Unbilled Activity tells you nothing about what the unbilled expense is or who the vendor is, just the customer and total amount. Instead, in QBO, Reports>Who Owes You (silly name for section when "Customer" is sufficient) and select Uninvoiced Charges to see report labeled Unbilled Charges. This report will give you detail of expense account, vendor, date of each detailed uncharged charge.
Now, why does Uninvoiced Charges not produce a report called Uninvoiced Charges or better et, why is it not named Unbilled Charges to select the report to match what it says on the actual report - oh, wait, this is Intuit, that explains duplicity In-two-it, its in the name, lol