This is part of why I bought an E4xx instead of a T4xx, the RAM isn't soldered on in the E4xx line, so that's at least one thing I can fix that I can't on a T4xx.
Only the TXXXs models come with soldered memory. I can easily change memory, SSD, keyboard etc on my T470.
The t490 not s has soldered ram. I think even rhe 590 has soldered ram (at least one slot)
Yeah, non-s versions are better in that regard, because t490s has RAM soldered (and t480s had one chip soldered + one upgrade-able module), I have it and no way to upgrade that.
I really hope EU will pass a law that will forbid soldering RAM and SSD to the mainboard, because it starts getting ridiculous and increases garbage.