Folder Structure altered or changed after ripping and tagging

After ripping a CD with EAC and tagging with mp3tag the folder structure in Windows Explorer becomes changed. Formerly I used to sort by composer, but now there are a lot of new folders titled with the names of artists resp. interprets. The mp3 files have been taken out of their still existing folders and get inserted into the new folders. It takes med a lot of effort to reinstall the old system. Is mp3tag the cause?

No.
Mp3Tag is able to change a folder-structure with actions but it does not do anything of that of its own.

Which functions do you use in MP3tag to tag the files?
E.g. if you use one of the convert functions, esp. Tag-Filename, you might get a new structure. Yet, this does happen automatically but only on the user's initiative.

Actually, you can use MP3tag to restore the old order by renaming the files or folders with data from the tags.