Describe the issue

The size property, for a slime at least must be 1 higher than Optifine in order to match the same sized slime
This probably extends to other entities as well, but I haven't tested any.
This issue may possibly affect random entities in EMF as well.

assets/minecraft/optifine/random/entity/slime.properties

First .properties:

skins.1=1
sizes.1=0

skins.2=2
sizes.2=1

skins.3=3
sizes.3=3

skins.4=1

Second .properties (sizes incremented by 1):

skins.1=1
sizes.1=1

skins.2=2
sizes.2=2

skins.3=3
sizes.3=4

skins.4=1

Slime textures for testing
slime2
slime3

Screenshots

Optifine (with 1st .properties):

ETF (with 1st .properties):

ETF with second .properties (incremented by 1):

Your setup: (please complete the following information):

• Minecraft version: 1.20.1
• ModLoader: fabric
• ETF Version: 4.3.3

This has been identified in my discord and will be fixed in the next version

resolved in version 4.5.0