Honestly not even WOTC knows or cares what Dragonborn look like.

The Descent into Avernus campaign has one with a tail.
The original Dragonbron design worked for those people that designed them, but later artists got confused by the proportions and represented them as dwarves only overiszed with a big crock mouth and dreadlocks.

5e basically forgot anything about the Ecology of the Dragonborn article anyway and i think at this point they just mean "play dragon people" and not somehting with a clear aesthetic.
For example 5e basically confirms the much regurgitated headcanon that dragonborn have the skin colour of their breath attack, when they are all supposed to be roughly brownish coloured.

I liked that in 4e, they were a race of their own rather than just dragon people. But 5e tends to forget about stuff like that.