Downloaded Files are Corrupted

Hi,

Our development version suddenly started downloading the attachments as corrupted files.
FA system is a previous one modified to run on PHP 8.2.
Everything was fine even after conversion till January 2025.
I guess something we have done has gone wrong.

When the file is opened in the server "attachments" folder, with adding the file extension, file opens without any issue.
Once it is downloaded can not open and file corrupted message appears.

Can someone familiar with file downloads reply / contact me?

Thank you.

Sunethra