You'll find them where people aren't hunting them. I see them at the bridge occasionally. I've seen them at shallower depths too. A few months ago, I speared a bunch of small ones at Breakers.So they just went deeper?
I've been diving a private boat lately and we hit spots less traveled. Any time I see some ledge, I find a few lionfish hiding. A few weeks ago, I speared 2 x 16 inchers and someone else got one too.
Are they deeper? Probably. I've seen videos of divers on some deep wrecks and LF were everywhere.