A Dremel multi tool could shave the face of the box flush to the drywall in seconds.

There could be a lot going on there. Faceplate screws for paddle switches are typically very short because the holes in the switch that fasten the plate are right in front of the mounting surface (sheetrock or tile, for instance) and force the device outward more and more as you turn the screw.

This can also happen with the box itself, especially if the installer uses an internal clamp screw as the ground screw and there is not enough space in the wall cavity behind the box, or if the internal clamp screw is not appropriately shortened.

it's misalignment of the box. I replaced original toggle switches with the rockers and the original faceplate and switches had the same problem. The installer was an apprentice, drunk, or thinking about his hot date that night.

If it's a plastic box, don't Dremel off the face flush. It appears you would have to slice through the switch screw hole of the last gang, which would lose the threads (or lose the steel clip if the other kind). Though something looks wrong with the box, it doesn't look angled because the middle gang is flush, just the outer gang is extended - it's like a 2-gang had a box extension jerry-rigged. Take off the coverplate. If the box has nails/screws on the interior, all's set, just pull all the switches/wiring out and reset the box. If it were a metal box, I have hammered them back in line before.

OK, I took the faceplate off one of the problem 3-gangs and took the switches out. I believe this box is nailed to a stud pack on the left. I think you can see the box edge is behind the drywall on the left and sticks out on the right. If I push really hard on the right I can get it even with the drywall but not as far back as on the left. This one is on the inside of an exterior wall and it looks like what may have happened is that spray foam insulation was applied after the box was installed and is pushing it out on the right. The other box is on a fully interior wall so would have a different cause for the box being crooked.

I tried not tightening the screws much on the switches, thinking that would not pull the box outwards, but I guess the faceplate screws into the switches, so they then push outwards on the faceplate.

Thank you. I was wondering if there was something like those box supports, I'll definitely try that I don't think my 3-gangs have blocking like in your picture. For example, if I run a stud finder over the top and bottom of the side of the box opposite the known stud, it does not come back with a hit. Also, if I'm looking at your picture correctly, if the box has the tab on the right connected to the floating block, I won't be able to use the box support, will I? It won't slip in between the box and floating block? If I can use the support smokestack then it is another sign there is no floating support? The house was built in 2019.

Don't be afraid to shave the drywall more to the right of the box so you can see beside it. You have plenty of room that the coverplate will hide. Try the Madison clip, only $0.55ea. I don't think there's a block though if it's freely pulling out.

There are a couple other clips I've seen, one is meant for a stripped screw hole but I believe will catch on the back of drywall, it goes on top/bottom if you're having problems on the side.

The other is a Raco old work switch box support, a bit bulkier.