The current X1 Carbon has an excellent trackpad, to the point that I actually consider the trackpad a usable alternative to the stick.

Palm detection is pretty terrible still though (on Linux at least). Tap to click is unusable for me for this reason.

libinput has much better palm detection than synaptics.

Personally, I haven't had tap to click enabled for a long time, since I have physical mouse buttons available.

I don't know why Lenovo doesn't just flat out copy the behavior of Apple's trackpad.

I dont know. But the keyboard got slightly worse.