When 1.15 came out I updated my 1.14.4 hardcore server to 1.15. The original untouched world and my edited world merged so that half the world is untouched and half of it has my edited world, meaning i lost half of my builds and things were cut in half (image attached). This is just corruption from updating and i know that that happens, however there was then another bug. I fixed up a lot of stuff over a few hours of work, throughout which i had logged off and on multiple times with no more issues. Then suddenly when i logged back on the chunks had all shuffled around in the area of my buildings (attached).