quwanger Is it better to have it off than to use Google's servers?
No.
GrapheneOS: you avoid Google's servers, but your ISP or mobile network can see that you are using GrapheneOS
Google: you look like a regular Android user to the network (if you are using a VPN)
Off: stuff breaks. You almost certainly don't want this.
GrapheneOS also adds the ability to fully turn Off the connectivity checks. This results in the OS no longer handling captive portals itself, not falling back to other networks when some don't have internet access and not being able to delay scheduled jobs depending on internet access until it becomes available.
https://grapheneos.org/faq#default-connections