In Windows, Unren extracts pictures as .jpg, whereas in Linux they are extracted as .webp...
Impossible. Really.
Unren does not modify the filenames. They're just patched through.
I think it's possible your OS does there something (?) or you misread something. e..g The format specifier from the file magic your OS identified, with the name extension. Could it?
There are some games here which use webp images but with their old file extension like jpg. Summertime Saga is such a example. This could be the case here.
... Any idea how to fix this? so I don't have to manually rename hundreds of files?
For me on Linux there are many options like the "rename" tool. Basic behavior:
rename (option) 's/oldname/newname/' filename.ext
So in this case yolu could do:
rename 's/\.jpg$/.webp/' *.jpg
This will rename every the extension from
jpg to
webp in every filename ending with
*.jpg If the jpeg's have the
e in the name then change both!
On windows you could go with XNview. A good app.