K-9 6.000 crash on Lenovo P11 Andr.11

Hello, I just installed K-9 6.000 via fdroid (g. not confirmed/skipped) and can see the list of incoming mails.
But when I try to open it on Andr. 11, the app shortly shows the header and crash.
It does not help to disable animation or to try it in landscape/portrait.
Debugging is activated, but to whom can I send it?
Old github password does not work and e-mail to reset does not work.
Same 6.000 version on Android 7.0 is working well.

Can you extract the stack trace from the log and post it here?

It should look something like this:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.fsck.k9, PID: 7717
        at com.fsck.k9.fragment.MessageListFragment.doPositiveClick(MessageListFragment.kt:1163)
        at com.fsck.k9.fragment.ConfirmationDialogFragment.onClick(ConfirmationDialogFragment.java:80)
        at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)