Mismatch between File/@Id behavior and documentation

[appel1]

• Which version of WiX are you building with?

WixToolset.Sdk/4.0.1

• Which version of .NET are you building with?

dotnet 7

• Describe the problem and the steps to reproduce it.

The documentation at https://wixtoolset.org/docs/schema/wxs/file/ states the following:

Id (String) : The unique identifier for this File element. If you omit Id, it defaults to the file name portion of the Source attribute, if specified. May be referenced as a Property by specifying [#value].

But given input like this:

<Fragment>
  <Component Id="OtherProject">
    <File Source="$(var.OtherProject.TargetPath)"/>
  </Component>
</Fragment>

I get an id like filO1gNj6vgqzhB7GVkA2C1ujporp0 in the resulting .msi.

Am I misreading the documentation or is the docs or implementation incorrect?