Out of interest, were you running the same version of balenaOS on both devices? (RPi3 and RPi4) Which version exactly?
I’ve found this other thread where the network interface is renamed through an udev rule, which sounds promising: Rename network interface
And also this other page (not balena specific) where they mention that a network interface could be renamed through a NetworkManager connection profile (nmcli connection modify ...): https://www.thegeekdiary.com/how-to-set-a-custom-interface-name-with-networkmanager-in-centos-rhel-7/
Perhaps you could try one of these approaches and let us know how it goes? 