+++Sorry this post had spelling mistakes and bad grammar - will clean this up +++

Have noticed a few odd events involving a creature who dies while caught in a spider's web

Real creatures in spiders web
If a real creature dies it falls to the ground, then vanishes followed by beam of light.
The spiders web is left for a few seconds before it too sinks into the ground.


Subverted creatures caught in a spiders web
If a subverted creature dies then creature falls to the ground, vanishes followed by beam of light along with the web in one go.


Illusion creatures caught in a spiders web
If a illusioned creature dies then both creature and spider's web disappears instantly.


Are these bugs or so weird occurrences?