When it starts to snow the leaves stay green, you have to save and quit and reload your world for the leaves to start the transaction from green to the silver snow covered colour, also if you go through a portal to the nether then back again the leaves start to revert back to green even tho it’s still snowing,,, again you have to save and quit and then reload the world for them to start the transaction again to the snow covered silver leaf, I play in the natural texture pack but have tried various others texture packs with the same results.