The behavior of players catching on fire after being hit by certain burning mobs was introduced in a recent Preview, but it doesn't match the way it works on Java Edition.

On Java Edition, players only have a certain chance of catching on fire, and the duration of the fire is not consistent either (The wiki says it's defined by the regional difficulty, but I haven't properly dug into it). The newly introduced behavior makes it so the player always catches on fire on normal and hard difficulties, and always for the same amount of time.