When PlayerEx is installed along with Cammies Wearable Backpacks, the tabs overlap and the backpack tab becomes almost entirely hidden. In the image below the backpack tab is just barely visible behind the book tab from PlayerEx. I wasn't sure if this was more a compatibility issue with this mod or caused by PlayerEx.

Mods Tested
camsbackpacks-2.12.jar
cloth-config-8.0.75-fabric.jar
data-attributes-1.2.3.jar
fabric-api-0.58.0+1.19.jar
playerex-3.3.4.jar

yea, it'd be a compat issue. I can see about fixing it tho, seems we both use similarly sized tabs. with no event, it means one of us is gonna have to budge when the other's installed. not a big deal tho

thanks for the report ^-^

Since I'm currently playing with these mods you could implement a Modcheck at the start of the Client.
If PlayerEx is loaded you could replace the Tab in the Inv with a small button besides the crafting book f.e.
This way you could also avoid some other mods which could be incompatible and just add their id to a list which gets checked on load

given playerex has more tabs, it would make more sense for them to move theirs over. moving the tabs is genuinely easier than making a new button