Found this issue while trying to add more actions to entity of MC-269830.

Sheep and bogged both have the "Sheared" entity data. The difference is while the "S" into "Sheared" sheep entity data is capitalized, the "s" in "sheared" bogged entity data is not. While this might seems like it doesn't matter, capitalization DOES matter for entity data. For instance, the command "/execute as @e[type=minecraft:bogged] run data merge entity @s {Sheared:0b}" does not gonna work. This could cause confusion for commander like me.

To reproduce, spawn a sheep and a bogged, then "/data get" each mob.