I might have been able to reproduce the issue on Minecraft 1.21.11: https://www.youtube.com/watch?v=AGtHhq0tCiA. At around 1:10 into the video I start getting a flood of “Chunks failed to save“-errors and after around 1:20 chunks start failing to load as described in the original bug report.
Scalies' Nest
I might have been able to reproduce the issue on Minecraft 1.21.11: https://www.youtube.com/watch?v=AGtHhq0tCiA. At around 1:10 into the video I start getting a flood of “Chunks failed to save“-errors and after around 1:20 chunks start failing to load as described in the original bug report.