Invisible blocks on some servers

[HashimTheArab]

When connecting with gophertunnel, many servers have "invisible blocks", hive, cubecraft, this exists on mostly every server.
These blocks are not there in vanilla, but on many servers these invisible blocks can appear in the place of air, chests, or any other block. Instead of seeing obsidian, it appears to be invisible bedrock.

I've noticed by testing on play.ubgnetwork.fun that instead of individual blocks it's the entire column of blocks that's invisible. I haven't verified if this is the case on every server. This does happen on servers without custom blocks.

For some reason, this block of code fixes it, no errors are outputted

case *packet.LevelChunk:
    c, err := chunk.NetworkDecode(air, pk.RawPayload, int(pk.SubChunkCount), world.Overworld.Range())
    if err != nil {
        fmt.Println("error processing", err.Error())
        c = chunk.New(air, world.Overworld.Range())
    }

    data := chunk.Encode(c, chunk.NetworkEncoding)
    chunkBuf := bytes.NewBuffer(nil)
    for _, s := range data.SubChunks {
        chunkBuf.Write(s)
    }
    chunkBuf.Write(data.Biomes)
    chunkBuf.WriteByte(0)
    pk.RawPayload = append([]byte(nil), chunkBuf.Bytes()...)
    pk.SubChunkCount = uint32(len(data.SubChunks))

https://youtu.be/v15Z8yQcwE4

invis.mov

[GameParrot]

Does it only happen on servers with custom blocks?

[HashimTheArab]

I'm not sure but this could probably be the case
Edit: It happens on servers without custom blocks too

[GameParrot]

The hive is playable for me (no block issues) with gophertunnel
I am using a custom protocol to forward start game packet and fix the falling issue