Minecraft 1.20.1
Litematica v0.15.3 | MaLiLib 0.16.1 | litematica-fabric-1.20.1-0.15.3.jar | malilib-fabric-1.20.1-0.16.1.jar

I'm trying to place a schematic in my world but when I place it, it's incredibly offset from where I placed it. Here's a picture of what's going on.

I'm pretty sure this has never happened before to me, please help!

You have had the Manual Origin option enabled in the area selection when saving the schematic, without actually setting that origin anywhere sane near the actual build. And the placement sub-region(s) are now at the same relative offset from where that manual origin happened to be from the area selection sub-region boxes.

You can either fix the area selection (disable the Manual Origin option in the Area Editor menu) and save the schematic again, or if that's no longer possible, then go to the placement configuration menu, and then to the sub-region's configuration menu, and just move that sub-region to where you are. But if it's a multi-region schematic, then it would be hard/annoying to try to keep the correct relative positions between the sub-regions like this.