Yes, it strange. Bubble column, waterlogged block, seagrass, tall seagrass, kelp & kelp plant also work too. 🙂
And yes you can troll your friends with that 🙂
MC-240251
Light block can block water & lava
Resolved
Duplicate
1
Thank you for your report!
We're actually already tracking this issue in MC-221590, so this ticket is being resolved and linked as a duplicate.
However, that ticket has been resolved as working as intended, which means that this is not considered a bug and won't be fixed.
Please be sure to use the search feature before creating a ticket to see if the issue has already been reported.
Quick Links:
📓 Issue Guidelines – 🛠 Community Support – 📧 Mojang Support – ✍️ Feedback and Suggestions – 💬 Mojira Discord