The _content folder should only contain static resources from shared razor component libraries (RCLs). Static resources can be extracted from shared RCL Nuget packages by executing a Publish task on the module's Server project to a local folder and copying the files from the _content folder which is created. Each shared RCL would have its own appropriately named subfolder within the module's _content folder.

ie.

/_content
  /Radzen.Blazor
    /css
    /fonts
  /syncfusion.blazor
    /scripts
    /styles