Cave vines generate without tip if they are generating too long to fit into the cave.
How to reproduce:
Travel around that lush cave there and it should happen regularly. Due to MC-219200 it might be in a different place each time
The "prioritize_tip" setting of the "minecraft:block_column" feature is behaving the other way around than expected: setting it to false would instead prioritize the generation of the tip.
The Cave vines would have a tip and wouldn't generate without one