For a comprehensive list of other examples of issues with 2D planes in models not being mirrored as expected, click here.
The bug
The planes composing dripleaf plants do not mirror on the back as one would expect, resulting in physical/illogical weirdness.
How to reproduce
Place a large dripleaf
View the light pixel on top of the dripleaf
View the leaf from below
Note that the position of the light pixel has shifted
Relates to MC-190774, MC-199237, MC-199239, MC-199241, MC-199242, MC-199248, MC-201748, MC-201750, MC-201751, MC-201753, MC-201760, MC-202595, MC-202598, MC-203036, MC-205158, MC-206570, MC-212305, MC-214693, MC-214694
Can confirm.