I notice in the mail-list on 20 of Jan 2018 that:
I would also like to add that snapshot 0117(!!!) introduced the new btrfs
default subvolume layout

Any fresh installation of Tumbleweed using the default btrfs root
filesystem will no longer have multiple subvolumes under /var (eg
/var/lib/mysql, /var/cache, etc) and instead have a single unified
/var subvolume...
By Richard B.

Ohoj, -I have whined as usual on every test for a couple of years that why is it showing a lot of sub volymes (/var)? Maybe I was whining by the wrong reasons but..

Tested today:
-openSUSE-Tumbleweed-DVD-x86_64-Snapshot20180121-Media.iso
-openSUSE-Leap-15.0-DVD-x86_64-Build84.1-Media.iso (2018-01-04).

I hope that SuSE 15 and Leap 15 will have in the end

Regards