I figured as much, but wasn’t sure.
If it ships with Monterey, there will be no way to go back to Big Sur unfortunately. I really wanted to go back to Mojave on my 16” when I got it, but there was no way. I only finally updated from Catalina to Big Sur a week ago and it feels mature and stable, I’d like to stay there too for a bit. I usually only update to a new os around when the one after it comes out, I want the most stable version possible. Catalina was a mess when I first got my 16” but it became very stable at its last update, right before Big Sur came out. Oh well