In the latest 1.17 pre-release 1 on Java Edition, the small dripleaf model has been changed to avoid z-fighting and overlap between the leaves. However, this is yet to be fixed on Bedrock Edition.
MCPE-129129
Small dripleaf leafs can overlap each other and cause z-fighting (parity issue)
Open
11
(Unassigned)
541391
Confirmed
Multiple
vanilla-parity
1.18.10.21 Beta, 1.18.10.20 Beta, 1.17.30.20 Beta, 1.17.11 Hotfix, 1.17.20.22 Beta, ..., 1.17.2 Hotfix, 1.18.0, 1.18.30.30 Beta, 1.18.30.31 Preview, 1.18.12 Hotfix
Retrieved
Affects 1.17.40.20