gnome-shell-classic from GNOME:STABLE:3.34 project
Select Your Operating System
Add repository and install manually
For SLE 15 SP2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/GNOME:STABLE:3.34/SLE_15_SP2/GNOME:STABLE:3.34.repo zypper refresh zypper install gnome-shell-classic