Wrong answers everytime

We have 8 sales invoices combined in one pdf document, the file is uploaded in OneDrive, I started asking questions from the file using Copilot, one of the questions is to give a total of all invoices, I got the right answer but when my colleague asked the same question to the same file, he got a wrong answer.
I face the same problem with other files also, getting wrong answers every time (One thing I have to mention here is that all those files are in Arabic language).
So, is it a language issue or is it the normal behaviour?

I even created custom Agents from SharePoint Library with only limited files but still getting wrong answers from Copilot.