Weirdly, the version field is actually irrelevant. You can't determine the type of a packet by looking at its first byte; you must look at the EtherType header in the Ethernet frame, or whatever equivalent your L2 protocol uses. It's redundant, possibly even to the point of being a mistake.
I mean, yes, in practice you can peek at the first byte if you know you're looking at an IP packet, but down that route lies expensive datacenter switches that can't switch packets sent to a destination MAC that starts with a 04 or 06 (looking at you, Cisco and Brocade: https://seclists.org/nanog/2016/Dec/29).
