kstars/ekos is a lot to grasp! In your local (laptop) ekos profile, when you select remote host, any indilib request for hardware by ekos or kstars (or any indilib client) be it a camera, telescope mount, gps, weather sensor, etc, are all forwarded over the network to the remote instance of indilb. kstars and ekos are still running locally.
If you had all your hardware directly connected to your laptop, you would then select local, and all the indilib device requests would be handled by the local indilib server.
I noticed the same thing as you. A VNC connection to the pi4 with kstars was not the best and performance really suffers. I removed kstars from the startup script on the Pi4, no need to have it running for my needs.