1463
All the other brands went along
(slrpnk.net)
This is a most excellent place for technology news and articles.
Even the latest P series:
https://laptopmedia.com/au/guides/how-to-open-lenovo-thinkpad-p14s-gen-4-disassembly-and-upgrade-options/
You can only add/swap a M.2 SSD, and WWAN modem.
They've added upgradable RAM with the Gen 5 models. The WIFI card is soldered, though, which isn't as bad but still meh for longevity IMO
Even worse, build quality and durability is significantly worse due to Lenovo making the T and P series Thinkpads thinner and lighter.