I have a few textures(mostly procedural noise) set up use WCS mapping, and as I copy and paste them around to make variations the scaling in the texture gets changed. I don’t know if it’s related but it’s also common for WCS mapped textures to have the size settings labeled “Repeat” in the UI on opening.
Can you post a file please so I can make sure I understand correctly? The texture will change with WCS due to object location I believe but the scaling changing sounds like a bug unless the texture itself is the cause.
If I have a texture in one material and I copy/paste it into another material or another slot somewhere, the Scale values get changed, by what looks like it could easily be that(come to think of it pointless) “conversion factor” that gets applied when you turn WCS mapping on or off.