DO NOT REPORT AN ISSUE IF YOU HAVEN'T TESTED THE ISSUE WITH THE LATEST VERSION IN CURSEFORGE
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Industrial Foregoing Version:
industrial-foregoing-1.19.2-3.3.2.2-4
Titanium Version:
titanium-1.19.2-3.7.2-26
Crashlog If Applicable (Upload to pastebin/gist):
n/a

If you open the keybinds menu to (re)configure the key for opening the Infinity Backpack, the keybind is missing from the menu.
If you copy the keybind from options.txt from a 1.18.2 version, it still doesn't work.

So the entire keybind is broken, not just missing from the menu.

On the 1.19 (nondefault) branch, I found a reference to the keybind
OPEN_BACKPACK = new KeyMapping("key.industrialforegoing.backpack.desc", -1, "key.industrialforegoing.category");

and the keybind itself.
"key.industrialforegoing.backpack.desc": "Open Infinity Backpack",

However I cannot tell what's wrong by these.

Since the issue author mentioned this on the Forge Discord, I took a look at the referenced keybind registration. The cause for the keybind not being registered is that the RegisterKeyMappingsEvent handler is being registered to the wrong bus, that event fires on the mod bus and not on the Forge bus: https://github.com/InnovativeOnlineIndustries/Industrial-Foregoing/blob/1.19/src/main/java/com/buuz135/industrial/proxy/client/ClientProxy.java#L94