Sorry in advance for the bad photos, but that's the best my phone could do in that lighting

The pot is 6" terracotta that they just got repotted into this Spring.

The soil is 50 perlite 50 regular soil.

I'll start by saying I don't know about pregnant onions (except that I thought the first person I saw talking about them was pulling my leg). It does look like what happens to overwatered/underwatered spider plants, and it doesn't sound like you're overwatering, but rather than assume anything I'll ask more questions that will help figure things out.

How often in general do you water it, and how do you decide whether to water? Did the problem start when you moved it away from good light or before then? Did you make any changes the previous time its leaves browned that could have caused the problem or fixed it after it appeared?

In general I'd say 2-3 weeks and I try to water it by looking at the wooden skewer I put in the soil. Usually when it's dry down at least 2 inches or more. But since it's in a window secluded from my other plants (except the other succulents) I often do forget about it at times and associate it with the same water needs as my other more drought tolerant succulents. But it's never been extreme to the sense that the soil is bone dry and the bulbs are shriveled nor has it been in this spot long enough for anything like that to even occur. They have always stayed nice and plump. Nothing that it hasn't gone through during the summer when it didn't have this issue. Since I've moved it I've watered it once.

I just noticed it happening today and it definitely wasn't happening before I moved it.

I don't remember doing anything different when it happened the first time. It just came and went away.

Maybe it's just adjusting ? Though they don't seem like the type of plant that would be finicky like that....

I'll try watering it more and see if that stops it... if not maybe I'll have to switch it out with my COT and put it back upstairs.

What's a COT?

I didn't realize it's a succulent, which shows how much I know. If it is, you might post over at the Cacti and Succulents forum.

Crown of thorns ;)

Sorry, is the Pregnant Onion a succulent?

Yes

I'll make another post in the Cacti and succulent forum if it continues to happen. Keep forgetting there are other forums besides House plants :)

It's easy to do, especially because lots of succulent issues come up here because so many of us grow them. And sometimes we don't even know what we have. Heck, I just brought a ponytail palm home from a coffee shop to repot it and give it some TLC, and when I searched the forums I was very surprised to discover that it's a succulent!