The 3.43 is okay. There are many Nano clones with different schematics and the original Arduino Nano has been changed as well. The latest schematic of the official Arduino Nano shows that the FTDI chip is powered from the 5V and not from the USB as it was in the past.
There is no 3.3V voltage regulator, but the usb-serial chip (either the FTDI chip or a CH340G on clones) generates 3.3V.