Login redirect

Hey guys,

I have a problem. When I want to log into my backend, I get a redirect. It doesn´t matter if I try /wp-admin or /wp-login.php. It always ends on that url: http://website.de/wp-login.php?redirect_to=http%3A%2F%2Fwebsite.de%2Fwp-admin%2F&reauth=1

It also doesn´t matter which IP or which device/browser. I cleared all wp-caches, deactivated all plugins and renamed the htaccess. Same thing. All paths in the wp-config are correct.

Folders have that scheme:
Root > data > wp-content
Root > folder01 > wordpress

It´s like that since last friday for the customer and for me it appeared like that yesterday morning. The customer did update a few plugins and uploaded something to the data folder via FTP.

Now I don´t know what to do.
Can anybody help me?