What is implied if plumage genes show high shared variation between species diverged fifty thousand years ago?

Selection pressures favoring color distinction were weaker or slower to establish than ongoing genetic drift or hybridization.

If two species that diverged fifty thousand years ago exhibit a high degree of shared variation specifically in their plumage genes, while potentially showing divergence in genes controlling other functions like migratory timing, this implies a specific imbalance in selective forces. It suggests that the evolutionary pressures necessary to drive rapid divergence in color to maintain species boundaries were either less intense or slower to become effective than the ongoing processes of genetic drift or occasional hybridization events that allowed the color-related genes to spread and remain shared between the lineages. This indicates that color distinction was not a primary, rapidly evolving barrier initially.