I suspect that error came from the old kubuntu install; the standard install isos don't use grub IIUC (Ventoy and mbusb ones do, but you said you used etcher.)
To boot from the USB, did you press F2, or F8, or F12 (it varies by manufacturer) to get a boot device choice?
To boot from the USB, did you press F2, or F8, or F12 (it varies by manufacturer) to get a boot device choice?
Comment