Harvesting weeping vines with silk touch (I tried with diamond and netherite pickaxes) corrupts them in the user's inventory.  They appear to place, but do not remove from inventory.  Reloading causes them to disappear, bone mealing them causes them to disappear, breaking them causes them to disappear without dropping and without dropping ghost vines below.  They cannot be dropped from inventory without removing them manually with the inventory open.  Having them equipped prevents interaction with chests/hoppers/etc.

Also: scaffolding glitches out around these ghost vines.  In particular, placing scaffolding on one of them replaces all connected ghost vines with ghost scaffolding.