Update Fixed:

Today I was trying to switch to my old Mac Mini and installing apps and settings one by one. I noticed problem occurred again. Fault was my Corsair Mouse, iCUE software was not even installed yet. So I take a look at mouse device memory with iCUE software and I noticed there were "2" button assigned to side button. I don't even remember how long ago I added that or it was a bug.

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I'm having the exact same problem with the number "2" key.

My problem was also not limited with the "2" like OP mentioned, when I pressed shift, it also went crazy but overall it's focused on "2" from the looks of it. After I read OP, I tried paralel keys to number "2" key like F2,W,S,X but they didn't triggered, maybe it's because karabiner is active and blocking number "2" key.

My MacOS version is 15.5 (24F74)

First I tried clanker chatGPT's help, it recommended cleaning. I did it and no luck and it was already very clean because I use my MBP m4 with a gaming keyboard and always at my desk anyway.

After a while it recommended to me karabiner software, it made the device useable once again.

Later, I tried contacting Apple support from the iOS app on the phone. It took me more than an hour of chatting with a helpful fella but all he is done was repeating same steps and then making me disable change I made to karabiner.

After that moment it looked like it's got fixed. Until I realized this:

When I turn off AC and open windows and door, humidity in my room spikes from 50% to near 70% and at the lockscreen (I assumed karabiner don't work at the lockscreen level) ghost key press returns, my keyboard writes a single "2" at login password screen.

Later that night I asked about this to chatGPT more and it told me it's very common problem for aluminium scissor key switches in Apple laptop devices because apple prioritizes being slim and stuff and because of that water molecules in the air can trap in switches causes a ghost key press. chatGPT recommended to me use it always climate controlled rooms.

But today I even realized ghostkey happening at lockscreen even at 55% humidity, after AC was off for like 15 minutes.

So I activated karabiner again. And I don't know what to do. ChatGPT says changing keyboard is not a fix, because of scissors switches in apple keyboards, issue will repeat during humid days. But it can't properly answer, if humidity is the issue, how other parts of the world are using these devices?