Supplementaries-1.19.2-2.3.4-fabric.jar
fabric-api-0.76.0+1.19.2.jar
inmis-2.7.1-1.19.jar
inmisaddon-1.0.4.jar

Latest Fabric Launcher on Curseforge (not sure how to check this)

We have Inmis and inmis addon installed on the server and have found a glitch where players are able to have an infinite inventory by placing INmis backpacks into a sack, and placing sacks into a inmis backpack.

Can't you do the same with shulker boxes?

Shulker boxes are turned off, you can not put shulker boxes in the backpacks (or the sacks I believe?)

I also mentioned this in the Inmis Github as I am not entirely sure which mod is in charge of it?

thing is sacks mimic exactly shulker box. they dont have a blacklist as they work on the assuption that if something can go in a shulker they can also go into a sack. If a mod were to disallow an item into a shulker then they wont work in sacks automatically

is this related to Supplementaries??? and is it resolved, if yes then please close.