Why some characters not allowed?

No. SharePoint cannot be configured to accept these characters in file names: " * : < > ? / \ |

These characters are blocked at the platform level because they are invalid in Windows, OneDrive, and SharePoint file systems. There is no setting, policy, or workaround that can change this. If SharePoint allowed these characters, OneDrive sync would break instantly, and so would many Office and Windows APIs. SharePoint follows Windows file system rules and some characters are reserved and can’t be used in file names.

If you need to use these characters, put them in the Title field or a custom metadata column. The Name field will never support them.

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