If your hair mods are going all gray too prematurely: (Middle-Aged stage should only display gray streaks)
You will need to change a value in the Material Instance in UE5 under the Variations tab.
The White DNA section is the key. The value for hair using vanilla textures should be around 0.85 and for custom textures I have noticed 0.49 typically works although it may vary.
Here is an example image with the hair Cazy converted for me. They were generous enough to send me the project file, and I discovered this feature through it!
P.S. White Age is a toggle switch that is not used in game. It’s simply there to preview the hair as it ages. I would still toggle it off after using it as a preview just in case it actually can mess things up in game.