thanks a lot for your support!
I’ve found also an old thread regarding this matter:
https://ww.wp.xz.cn/support/topic/x47lx4fbax4cx53%E2%80%B3-malicous/
thanks, you are right, but it’s sometimes not so easy to change a plugin.
and wp-filebase pro is a really excellent plugin by the way with a professional looking website: https://wpfilebase.com/. up to now i had no other problems than a conflict with wordfence because of base64 encoding, which is used for masking licence information (as i was told)