generation of equal mobs in minecraft java and bedrock

In Minecraft Bedrock, mobs spawn in a strange and sudden way. For example, I've seen several mobs appearing in my face out of nowhere, and when I move away a little, these same mobs disappear in front of me out of nowhere. Minecraft Bedrock's mob spawn is very bad and buggy, but in Minecraft Java, this process happens much more naturally and smoothly, without giving the buggy and strange appearance that Minecraft Bedrock makes it appear.