Whenever it snows in Minecraft, trees turn white. But if you enter a different dimension and return, this is disabled and all trees will remain green no matter what.
Work-around fix is to leave and rejoin the world.
Steps to reproduce:
Go into nether or end
Return to the overworld and enter a cold biome, like a cold taiga.
Make sure it is snowing
See how leaves begin to defrost even if it is still snowing.
Also affects Android in 1.19.60.26 Preview