I am curious if you would agree with me that the keycaps on the space invaders chicken lips are not pad printed but rather dye sublimated. They are PBT plastic not ABS and do not yellow, and PBT caps are usually dye sub.
100% agree. I've had a friend of mine in the SEA-CCC named Christian, who is also a member of this site now, talk to me about this very topic. Upon very close inspection I can confirm this. I have a DSLR with a fixed-lens macro and really got in there. These are definitely dye sub. As a result, they are actually a little fuzzy around the edges, but they'll never yellow or wear off from use.
I've also learned how to safely remove these keycaps, and they are extremely low-profile, which is pretty cool to actually see when you hold them in your hands. It's pretty wild.
Some of the keyboards from yesteryear are such achingly better than what I use in my professional life today. Heck my blue-tooth Mac keyboard (white) at work had half its letters wear off after just about 3 years or so. It's that old cliche: things just aren't made to last anymore!