and a bunch of strange

gcp:compute:RouterNat (bel-nat):
    error: connection error: desc = "transport: Error while dialing: dial tcp 127.0.0.1:39615: connect: connection refused"

This seems to be a network issue that could potentially be transient. Could you try running a

pulumi up --refresh

and see if that resolves it. If not, could you share the output of

pulumi up --logtostderr --logflow -v*=*10 2> out.txt

and I can take a closer look at the logs

with refresh it actually proposes to replace instances, unfortunately