For anyone wondering about the security issues caused by this, even if the windows partition is encrypted, it’s still possible to get secrets from the Windows install.
If you have root access to a Linux machine, you can easily replace the Windows kernel loader with one that looks just like Windows, but does nothing other than steal your encryption password on login/boot.
Secure Boot/TPM would protect against this, but Linux users (especially those that are more lax about security) tend to disable it as part of installing Linux.