20w13b is a snapshot that was released on March 26, 2020. It fixed a few bugs.
Fixes
[ MC-175177 ] - Emptying, breaking or blocking the spawn anchor creates ghost blocks in the Overworld when the blocks are destroyed. [ MC-175988 ] - Dying without a valid spawn point causes a softlock . [ MC-176004 ] - Impossible to interact with the world after death in the End or the Nether without valid point of appearance. [1]