Login error IOS App 3.01

I use Nextcloud 19.0.1 on Ubuntu 20.04 with nginx.
Since the Update of the IOS App to version 3.01 I can’t use the App anymore. The login is working fine but I get an error 401 “not authorized” and I can’t see any folders.
On my log I can see error messages like that "Login failed: ‘Firstname+Lastname’ (Remote IP: ‘xxx.xxx.xxx.xxx’)
Before the App Update when the pass was wrong error message was "Login failed: ‘Firstname Lastname’ (Remote IP: ‘xxx.xxx.xxx.xxx’)
I found some infos about webdav error, but no more posts about user with the same behavior.

best regards