Minecraft snapshot 24w45a introduces a new minecraft:xmas property useable by item model definitions; the chest and trapped chest item model definitions use this property to dispatch to a special model type with the minecraft:christmas texture.

I believe this naming to be an inconsistency within the game's resources as it generally uses the 'xmas' term consistently in other places, both within data and in user-facing strings.

Instances of 'xmas':

• Splash text: Merry X-mas!
• The minecraft:xmas property

Instances of 'christmas':

• Texture used by single chests and trapped chests: minecraft:entity/chest/christmas.png
• Texture used by the left side of double chests and trapped chests: minecraft:entity/chest/christmas_left.png
• Texture used by the right side of double chests and trapped chests: minecraft:entity/chest/christmas_right.png