R5-D4 is Star Wars royalty. He is a veteran of the Rebel Alliance. In A Certain Point of View, it's revealed that he purposely sabotaged his own circuits so that R2-D2 could complete his mission. More recently, he helped save Navarro from Gorian Shard's pirates by leading Captain Carson Teva to the Mandalorian covert. He's quite the little dude, and should be treated with respect, but Hasbro keeps omitting one key detail from his backside (at least in the 3.75 scale).
R5-D4 has three vertical stripes on the bottom rear of the drum:
The above screenshot is obviously sourced from A New Hope, but this detail persists right up to the recent events in The Mandalorian:
Despite this, the recently revealed Vintage Collection R5-D4 is missing this particular detail:
The thing of it is, Hasbro always misses this detail. They missed it in 1996 with the POTF R5-D4 release. They missed it in 2006 with the TSC 032 - R5-D4 release. They missed it in 2011 with the VC40 - R5-D4 release (and it's 2012 re-release in the Droid Special Action Figure Set). They just keep missing it...in the 3.75" scale that is. The simultaneously revealed Black Series R5-D4 has them:
It's somewhat surprising that there wasn't some cross-referencing between the two paint designs. The upcoming Vintage Collection release is using the Build-A-Droid sculpt. That means it's really a collection of accessories. If we're paying $17 for a small figure that was once "given away" as accessories, I think it's fair that we ask that Hasbro get the details as accurate as possible. Hopefully the paint applications can be tweaked before the production figures are released.