Server, win 10, java 17
When on a server at high coordinates, explosions from e.g. creepers or tnt will create ghost blocks.
This cannot be reproduced in singleplayer.
I know this bug exists at least since 1.16.5 and is especially annoying when you make some survival minigame that requires random spawnpoints and features creepers.
1. Start a local server
2. Connect to it and op yourself
3. Run /tp 20000000 ~ 20000000
4. Enter creative mode to avoid killing yourself
5. Run /summon tnt above some dirt, repeat in a few locations
Ghost blocks appear towards the positive coordinates (either positive x or positive z, depending on your exact location)
The server should update the client correctly.