libisofs6 from isv:Rancher:Elemental:Stable project
Select Your Operating System
Add repository and install manually
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/isv:Rancher:Elemental:Stable/15.4/isv:Rancher:Elemental:Stable.repo zypper refresh zypper install libisofs6