I have checked the file of ice plain biome and ice mountains biome, and I found that there is a 'frozen' tag in this file, which controls the spawning of the strays, but no 'monster' tag in it, which controls the spawing of the zombies, spiders, skeletons and creepers. As far as I am concerned, it must be a negligence to have omitted the 'monster' tag, causing there are only strays in the snowy tundra and snowy mountain.
Additionally, in Minecraft Java edition, hostile mobs, such as zombies, skeletons, spiders and creepers, can spawn normally.