Exactly what it says.
This is what it looks like:

Impossible? Not on Minimalist mode!

Granted, I have not yet seen a map that exploits minimalist mode like this but it can create unfair advantages when present.

Like walking around a decoration item that some people can just literally phase through.
Not a huge problem but it would be nice to have a rectangle ground to represent collision-based mice decorations.
Seeing how you can customize the decoration items though, I think it would be best if they are represented with a default colored rectangle ground arranged the same size as the decoration's hitbox.
It would make it easier to implement I imagine.
The only time it does not work is P22.
If this a bug, please ignore.
Here is another more extreme example:

/support

/support