This is a parity issue, since this is a feature on Java snapshot 20w30a.
Step to Reproduce:
1. Place down lantern/soul lantern
2. Put the water bucket in the block that is occupied by the lantern.
--> ❌ Doesn't get waterlogged
MCPE-92995
Parity: Lantern and Soul Lantern cannot be waterlogged
Resolved
Fixed
14
(Unassigned)
341196
Confirmed
Multiple
vanilla-parity
1.16.100.53 Beta, 1.16.100.52 Beta, 1.16.100.51 Beta, 1.16.100.50 Beta, 1.16.20.54 Beta, 1.16.1, 1.16.10, 1.16.21, 1.16.20
1.16.100.54 Beta, 1.16.100
Retrieved
Lanterns even get destroyed by flowing water and you also cannot place it underwater like torches.