grub-efi-amd64 cant unmount /tmp/zfsmnt.8wydX2

[Thomas Schweikle]

grub.efi-amd64 fails to unmount /tmp/zfsmnt.8wydX2. In tune a non working grub.cfg is created.
System boots into rescue mode, unable to mount zfs.

ProblemType: Bug
DistroRelease: Ubuntu 23.10
Package: grub-efi-amd64 2.12~rc1-4ubuntu1
ProcVersionSignature: Ubuntu 6.3.0-7.7-generic 6.3.5
Uname: Linux 6.3.0-7-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.27.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: XFCE
Date: Tue Aug 22 00:55:06 2023
InstallationDate: Installed on 2021-12-11 (618 days ago)
InstallationMedia: Xubuntu 21.10 "Impish Indri" - Release amd64 (20211012)
ProcEnviron:
 LANG=de_DE.UTF-8
 LANGUAGE=de_DE
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: grub2-unsigned
UpgradeStatus: No upgrade log present (probably fresh install)