2016 MacBook Pro, Keyboard replacement program. Keyboard still broken after the repair.

Unfortunately the issue with the keyboard is a design issue with the butterfly mechanism and Apple replaced the keyboard with another one with the same design so it is not unusual or unexpected to have the issue occur again after several years. However, I have noticed that the replacement keyboards tend to have less failures than the original one so perhaps Apple did make small slight modification to the design.

Try cleaning the keyboard using compressed air since it takes very little dirt to cause an issue. Here is an Apple article with instructions which you must follow exactly since tilting the can of compressed air can cause cold wet propellant to spray from the can of compressed air which can damage the laptop:

How to clean the keyboard of your MacBook or MacBook Pro - Apple Support

Another common cause of keyboard issues (affects all Apple keyboards old & new) is liquid residue that gets splashed onto the keyboard and solidifies between the very narrow gaps between the key cap and the key opening (sometimes the residue will also get onto the butterfly/scissor mechanism as well.

Unfortunately once the laptop is more than four years old the free Apple Keyboard repair program no longer applies. Here is an Apple article with the details of the free keyboard repair program:

https://support.apple.com/keyboard-service-program-for-mac-notebooks

You can always provide Apple with product feedback here (Apple will not respond):

https://www.apple.com/feedback/

You can also contact Apple corporate (Apple may respond back to you):

https://www.apple.com/contact/

The readers of your post are not going to be able to answer your very good question. This is because none of us represent Apple. We are folks just like you and participate in this community to help each other out with technical questions/issues.

My recommendation is that you contact ➡️ Apple Support

Axel F.