safari export excel with unknown file

Hi，

I have a web page and I launched in Safari on iPad or iPhone. In the web page, I can export the data to a excel file. I can choose .csv file or .xlsx file for the exported file type. When I choose .csv file, the exported file will be launched in safari. But when I choose .xlsx file. The file will be exported as file without file extension, and its name was "unknown". If I move the file to other place, just like oneDrive or Dropbox, and check the file name to add ".xlsx", the file could be opened.

I tested in other browser such as chrome and Edge, the file should be exported as "Data.xlsx"

Is it safari default behavior? the exported xlsx file could not be launched in safari and the file name would be changed to unknown