Quiet floors in deeper Dungeon?

[stoneychips]

Is there typically a quiet floor with low population somewhere between D12-D14?

I just did a D14 in v19 and it was eerily quiet. It looks like the level has probably all been cleared, from the space covered. What few monsters I can recall meeting:

One cyclops
One hound
One troll
One red centaur
Skeleton centaur
A crimson imp or two
One needle trap
One teleport trap

I picked up:
1 artifact flail
2 potions of lignification
At least 1-2 yet unknown scrolls (NOT acquirement haha)
1-2 yet unknown potions (NOT heal wounds, cure mutation, haste for example - one ambrosia)

By contrast, D13 was super packed with two herds of yaks, multiple shadows, skeletal warriors, a gang of centaurs, 2 hill giants and at least one cyclops. Possibly also some fortress I avoided for now, not sure if it was there or D12.

Is this normal, to have a kind of dead floor tossed in among the low ones? I think I've seen it happen before, but it was really dramatic this time.

[stoneychips]

I'm suspecting the Vaults entrance is on D13 inside that fortress layout, if that explains any of it. It has a blue orc warrior I can't quite hack yet so not quite confirming that now.

Edit: Yes, Vaults entrance was on that floor.

[tabstorm]

I had a D:7 recently where 0 monsters spawned. It happens.

[VeryAngryFelid]

I think it is a bug