The Yeti SB140 L comes with an Fox Transfer 31.6/175mm Post.
Riding today the seat popped off, not an entirely painless event. The dropper post upper clamp had failed at the front and the seat flipped back.
It seems this is not so uncommon:
Fox provides the schematics here, but not sure if they have spare parts.
2021 FOX TRANSFER SEATPOST Schematic
The broken part on my bench.
It was not possible to find the part available online, although Worldwide Cyclery do have it in their inventory, if currently out of stock.
The alternative is a $309+tax and shipping replacement post.
I did finally find one online with a wonderful bike shop The Inside Line in Calgary. They shipped the part and it arrived within a week.
Re-installation was pretty simple, sticking to the specified torque settings and this time have the seat not set so far forward as others seem to think that this is the setting that leads to the part failure.