Chunk flickering for geyser users

[noiverre]

Java clients from 1.21-1.21.10 have no issues and works flawlessly

Related information:

This server is running Paper version 1.21.4-212-main@bb1beda (2025-03-17T10:10:58Z) (Implementing API version 1.21.4-R0.1-SNAPSHOT)
This server is running Geyser version 2.9.0-b986 (git-master-80db983) (Java: 1.21.9, Bedrock: 1.21.90 - 1.21.123)
ViaVersion version 5.5.1
ViaBackwards version 5.5.1
BetterView version 2.1.1, default configuration
Simulation distance: 4
View distance: 4

I'm not sure if this issue still happens in latest 1.21.10 paper build

The flickering happened if geyser users use view distance further than the server's built-in view distance, to make it easier to notice just fly to sufficient height and move around

On additional note, some users reported chests being invisible at a seemingly random occurrence, simply reloading the chunk from client will fix this issue. Not sure if other block entities have this visual bug or not

[booky10]

Hmm, I am not sure if we can do anything about this
The chunk appears to flicker when the real server chunks get sent
Java simply replaces the existing chunk, but bedrock seems to have some flickering when the chunk sent by BetterView gets replaced; I will do some further testing regarding this tomorrow

[noiverre]

Rough guesses, could be some geyser limitation, or bedrock client themself
At least the issue is documented

[noiverre]

Interesting thing is that I found out I can replicate this, but instead of using bedrock client, I used java client with ViaFabricPlus and switch the client protocol to Bedrock 1.21.120. The chunk flickering still happen, now I am more concerned that this is something related to geyser

[booky10]

I skimmed through geyser sources and didn't find any special handling for replacing chunks
I don't know much about bedrock edition or the bedrock protocol, but this may just be a limitation by the bedrock client