My experience has been similar. I upgraded from the 2014 MBP (which is a glorious machine) to 2018. The day I got it, I realized it had issues with the keyboard (several keys repeating). Took it back to the store, got a new device. The issue wasn't as widely acknowledged back then. When I complained to the store that I was experiencing the same issue again, the gave me yet another device, same issue. Went back to the store and they got annoyed at me. They complained that none of their other customers reported this issue.

They accused me of installing apps that were causing this issue although I had nothing of that sort installed. I am a web developer and like to think that I know computers well enough to not install sketchy apps. I had installed all the same apps that were in my 2014 MBP so when I confronted the store, they just gave me a random reason and sent me away. I got so fed up trying to convince these people that there was an issue. I ended up buying a Magic Keyboard and using that instead.

Mind you, all this happened in India where Apple doesn't have a direct retail experience. 3rd party retailers have zero training procedures in place. Their staff isn't nearly as knowledgeable as their US counterparts about the products they are selling. This whole keyboard fiasco has been my worst Apple experience.