Hi! Recently me and some frineds wanted to reach the WORLD BORDER in vanilla minecraft. After reaching the border we encountered a strange bug. Whenever a tnt/creeper explodes a strange black shadow appears on some blocks. When walking into it you're getting kind of stuck and move verry slowly and buggy, and when placing a block or trying to burn it down with a flint and steel that specific buggy block reapears. I encountered this issue when i used the offical server jar (https://www.minecraft.net/en-us/download/server/), near the border and upon reconnecting all the buggy blocks reapear somehow. From my speculations the exploded blocks don't load correctly and that causes the wierd shadow.

We're playing on 1.16.5 .

Link to a showcasing video of the bug : https://www.youtube.com/watch?v=-cMzr5DXiQs&feature=youtu.be