ThinkPad T14s Gen 3 has a 6850U and is ~1mm thinner than T14.
You're right though, none of them are superthin (<15mm) like ThinkPad X1 Carbon or Dell XPS 13. Maybe it's not possible to cool these faster AMD CPUs in such a small volume? Nobody wants to type on a space heater.
Edit: found these pages with complete lists, hell yeah
https://www.ultrabookreview.com/36030-amd-ryzen-7-u-laptops/