For a comprehensive list of other examples of issues with 2D planes in models not being mirrored as expected, click here.
The bug
The plane composing the top attachment for spore blossoms does not mirror on the back as one would expect, resulting in physical/illogical weirdness.
How to reproduce
Place a spore blossom
View a specific section of the leaf, preferably a 2x2 area on the corner
View the exact same section of that texture plane on the direct opposite side
Note that the exact texture pattern at that position is different, even though it should be the same
How to fix
The resource pack attached to MC-237445 fixes this issue completely, alongside fixing multiple other issues with flat plane models.
The attached spore_blossom.json can also be used, however it "fixes" MC-214185 as well, which has since been considered intended.
Attachments
Comments

Can confirm.
Can confirm in 21w06a.

Can confirm in 21w07a.
Can confirm in 21w08b.
Can confirm in 21w11a.

Can confirm in 21w14a.
Can confirm in 21w16a.
Can confirm in 21w17a.
Can confirm in 1.17.
Can confirm in 1.17.1.

Can confirm this issue exists in 1.18. pre-1
Can confirm in 1.18.
Can confirm in 1.18.1.

Can confirm for 22w05a
Can confirm in 1.18.2.
Can confirm in 1.19.
Can confirm in 1.19.2.