Made an account here just to add to the list of issues with this keyboard.
Bought a 2018 15" MBP, essentially fully specced (i9/32GB RAM/1TB hard drive), at the beginning of November. Everything worked fine for a couple of weeks, after which I started to have a few issues mostly with the "s" key, though I would occasionally have issues with the "a," "e," and space bar keys. With some investigation, I realized that the frequency of the error occurring varied with the point of contact on the key; i.e., typically the error was quite rare when the very center of the key was pressed but become more frequent on certain sides/edges of the key. Eventually, the error became so frequent that typing with the built-in keyboard was totally unusable. I followed the "cleaning procedure" suggested by Apple with compressed air (lol) which didn't change a thing.
Went to the Apple store and got a replacement with essentially no questions asked. Simply demonstrated the error, gave them my original model, and got a brand new, identical, still-shrink-wrapped model. "Great," I thought. Problem solved. That happened <2 weeks ago.
I'm now having trouble with the space key on this new unit. I had done some preliminary research before buying this as I had heard the complaints of the butterfly keyboards on the previous models but assumed everything was taken care of. With two failed machines in a row, though, I figured it was time to do some more research. Lo and behold, others are having the same issue and I came across this thread.
As with the last unit, the error seems to occur more frequently when certain points of the space bar are pressed, but it happens frequently enough that it's quite irritating. I've installed Unshaky which seems to have largely resolved the issue as I was having problems with repeated key presses rather than not registering a key press at all, though the latter did and still does occur intermittently.
This is beyond frustrating. After having trouble with this second unit, I'm very seriously considering returning this unit and saying "**** it." I've got a fully specced 2013 15" MBP that I was using prior to this unit which still works reasonably well, though there are several issues with it (issue with the screen coating that I didn't realize there was a repair program for until after the program ended, needs a replacement battery, just generally somewhat sluggish, particularly for relatively demanding computing tasks) that make me want the newer model.
I love Apple products - or at least I did. My wife converted to a MBP after my experience with the 2013 model, which she loves. I pre-ordered the iPhone X when it came out last year. I've got an iPad Pro. And I'm all in on the peripherals, too, from a Time Capsule to AirPods. In general, my experience with Apple products as been outstanding, and I far and away prefer macOS over Windows.
But this is leaving a very nasty taste in my mouth. I didn't spend $4k on a laptop which is horribly overpriced for the hardware - something that I do willingly because I want to use macOS and generally like the quality of Apple hardware - to have basic problems with something as fundamental as the freakin' keyboard.
I'm going to give this unit a couple of weeks to see how it goes. If anything gets worse or other keys become involved, I guess it's back to the Apple store I go for another replacement.