That's the standard Android behavior for the USB gadget mode, not something specific to LineageOS, and it does not mean USB is in a charging-only mode but rather than no USB gadget functionality such as file transfer (MTP) is active. It does not mean USB peripherals and USB-C alternate mode are disabled, which certainly work in the default charging-only mode for Android's USB gadget setting. It doesn't even mean that USB gadget mode is fully disabled, only that it's in the MTP mode with MTP disabled. There's a slight difference between the regular and and more advanced setting: MTP mode with MTP disabled vs. no active USB gadget. The USB protection feature on GrapheneOS is for blocking new USB connections as a whole at both a software and hardware level and disabling USB data at a hardware level vs. that setting only controlling USB gadget mode. Most of the attack surface is in the USB protocol implementation and especially the USB peripheral drivers which are not disabled in the default mode Android calls charging-only since it's about USB gadget mode, i.e. using the phone itself as a peripheral.
That's the standard Android behavior for the USB gadget mode, not something specific to LineageOS, and it does not mean USB is in a charging-only mode but rather than no USB gadget functionality such as file transfer (MTP) is active. It does not mean USB peripherals and USB-C alternate mode are disabled, which certainly work in the default charging-only mode for Android's USB gadget setting. It doesn't even mean that USB gadget mode is fully disabled, only that it's in the MTP mode with MTP disabled. There's a slight difference between the regular and and more advanced setting: MTP mode with MTP disabled vs. no active USB gadget. The USB protection feature on GrapheneOS is for blocking new USB connections as a whole at both a software and hardware level and disabling USB data at a hardware level vs. that setting only controlling USB gadget mode. Most of the attack surface is in the USB protocol implementation and especially the USB peripheral drivers which are not disabled in the default mode Android calls charging-only since it's about USB gadget mode, i.e. using the phone itself as a peripheral.
Got it, that makes sense! Thanks for explaining :)
It is not the same feature as present on GrapheneOS. That is done through the OS while GrapheneOS makes kernel changes to physically shut it down.