I spawned skeletons onto waterlogged top slabs, and the second they moved they started going really fast (as if they had speed 3), so then i spawned creepers to try to kill the skeletons (I'm not good at commands) but when they exploded they didn't break any blocks
To recreate this behavior,
First, build top slabs
Then, right click every slab with water (or you can build the slabs in a lake and/or ocean
Next, spawn skeletons and creepers
Finally, watch as the skeletons go waaay faster than they are supposed to and ignite the creepers (with a flint and steel) and see as they explode and break NOTHNG.
Linked issues
Comments
Logdotzip- again covered this in his Oddest Glitches Still in 1.14.4 vid
Skip to 1:00
Thanks.
"skeletons go absolutely CRAZY" is not exactly a very helpful way to help us with reproducing this issue. Please take a look at the Issue Guidelines, linked below, before making further reports.
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Oh, okay I just changed it to say exactly whats going on.

Duplicates MC-156022
I split the creeper bug off into MC-158321. Skeletons moving so quickly is a consequence of them not being able to pathfind properly, which is already reported in the ticket that @unknown mentioned.
Please make sure that you're playing on Minecraft 1.14.4. There was a bug in previous versions that caused mobs to spin on top of waterlogged blocks.