ScreenMixin completely nullifies all other mods' functionality that may rely on the shift key by entirely cancelling the keystroke. Some alternatives may be:
a) use the loader's input event for compatibility
b) dont cancel the keystroke to begin with (why not do you logic, and let the keystroke pass through?)
c) check if the item in question is even a comparable piece of equipment

https://github.com/AHilyard/EquipmentCompare/blob/1.21-multi/common/src/main/java/com/anthonyhilyard/equipmentcompare/mixin/ScreenMixin.java#L38