Docker Sandbox images take a huge amount of space for no reason

I started from a very simple shell sandbox, where I manually installed Claude Code.
The first template save resulted in a 1.5GB image.

After that, I proceeded to install some very minimal bash tools, such as direnv, and did some custom bash environment configuration. I also added my rules/skills/hooks/MCPs to Claude.
On the 2nd template save, I got a 4GB image. No idea what added those unnecessary 2.5GB.
I attempted to inspect it using Docker Desktop but it doesn’t show any meaningful info.

Is this a known issue?
Or is there any way for me to inspect what’s bloating my image?

It is

do you also use Docker Desktop on macOS or any machine with SSD?