Having just launched gnome-calculator on my Ubuntu install, the resident memory size is 63768 bytes, or 63.77 kB. So I don't quite think that's an accurate depiction

It must no longer be launching an entire container just for it then.

It took a few seconds to launch too. It was possible to uninstall the snap and install the deb, fixing all these issues, but it wasn’t the default, and I gave up on Ubuntu around that time.