Attempting to use this on client and server side.

Minecraft 1.20.1
Forge 47.2.0
shrink 1.4.3

Appears when you include this in a server environment it gives this error

Mod File: /Shrink-1.20.1-1.4.3.jar
Failure message: Shrink (shrink) has failed to load correctly
java.lang.reflect.InvocationTargetException: null
Mod Version: 1.4.3
Mod Issue URL: NOT PROVIDED
Exception message: java.lang.RuntimeException: Attempted to load class net/minecraft/client/renderer/entity/EntityRenderer for invalid dist DEDICATED_SERVER

And when attempting to connect to the server with Shrink disabled it says that the server is missing the mod shrink |

Server Crash
https://gist.github.com/Zelioth/1434085be1addb29d5a2efa073e2f978

Looks like Using version 1.4.2 in server and client allows it to load perfectly. but 1.4.3 does not allow server to launch or client to connect without it being in server.

Can I get the full crash log?

Full crash log? The crash log I provided was the full server crash log on startup. Removing shrink or downgrading it fixes the issue. The client isn’t crashing it’s just refusing to connect to server without shrink installed or downgraded

Fixed in 1.4.4 https://legacy.curseforge.com/minecraft/mc-mods/shrink_/files/4784393