Coul be a several things. They should never see direct sunlight for certain. Where were they being grown in the store? If inside then possibly even the shaded outside is too bright.

Other than that overwatering is common if you potted them up.

Also could be a fert issue, but if the potting soil was one with small amounts of fert added it is unlikely.

Try giving it a break and see what happens. Remove the yellow leaves (they won't re-green), bring inside and don't water or touch it for a few weeks. Give it a good inspection for pests before bringing it in.

I don't know what the issue is, this is simply what I would do in your situation.

I have actually had the same thing happen to me. I wasn't sure exactly what it was and I still don't. I just let it be for a few weeks, only watered it when it got dry and it actually recovered itself. The longest vine I had lost all but like 5 leaves. But it is doing great now and have new sprouts coming up. Good luck, I hope it snaps out of it.

Overwatering sounds like the culprit to me. Monsteras need bright light and well draining soil. If your soil is heavy and peat based, it's going to hold more water. Did you amend the soil by adding Perlite or Sand for additional drainage? Also, if your plant was not rootbound when you bought it, you should not have potted up, especially now that the plant is getting ready for a winter resting period. You didn't mention how much larger the new clay pot was. How many sizes did you go up when you repotted?