i have noticed lately on the maps were mice can turn into objects, when they transform they glitch through the ground and die.

that happened to me at 801 too

I've had problems with this also,

You will pass through the ground when you transform, If you jump and transform, you will be on ground but if you despawn yourself you will fell through.
When you fell through and you jump onto the ground, you will not sink down.

And well you can pass through walls

This was happening to me as well

To avoid falling through ground... Jump and transform. This works. I have tried it.