The leaves in trial chambers "entrances" have the "persistant" property

The Mangrove leaves in trial_chambers/corridor/entrance_1 and trial_chambers/corridor/entrance_2 and the Oak leaves in the same rooms have the “persistant” value to true, making them not naturally despawnable.

How to reproduce :

execute the command “/place structure minecraft:trial_chambers”.
Find the appropriate rooms (might take some tries, should generate in a 4/9 chance)

Look at the block properties of the leaves (F3)