There's a bug with the texture several mobs are laggy some blocks also like the bed one
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This was fixed in 1.14.0.1 Beta.
https://feedback.minecraft.net/hc/en-us/articles/360034989811-Minecraft-Beta-1-14-0-1-Xbox-One-Windows-10-Android-
Not quite sure what you're referring to specifically, but I can see that the horse in the image is using the older model, so we can track that issue here.