Unfortunately, both installers used for Desktop Ubuntu flavors, i.e. subiquity and calamares, are currently able to properly install Ubuntu/Lubuntu/... into an encrypted partition with an LVM inside to allow multiple partitions (e.g. if other file systems are needed for applications like LXD), which is a regression.
In contrast, the old fashion console based installer for Ubuntu server is still able to do it properly.
What is the recommended and official way/workaround to install Ubuntu desktop versions into encrypted partitions with LVM?
Install the server edition, remove cloud-init, and install e.g. lubuntu-desktop?
Anything else needed?