This bug was fixed in the package initramfs-tools - 0.136ubuntu6.6
--------------- initramfs-tools (0.136ubuntu6.6) focal; urgency=medium
* Cherrypick zstd support from upstream. LP: #1932542
-- Dimitri John Ledkov <email address hidden> Fri, 18 Jun 2021 14:22:25 +0100
This bug was fixed in the package initramfs-tools - 0.136ubuntu6.6
---------------
initramfs-tools (0.136ubuntu6.6) focal; urgency=medium
* Cherrypick zstd support from upstream. LP: #1932542
-- Dimitri John Ledkov <email address hidden> Fri, 18 Jun 2021 14:22:25 +0100