Fatal error: Uncaught Error after update

hi,
we run several websites on different server. All runs with WP Cerber.

But as we run the last updates 4 our pages and one from a friend got a fatal error.
We tried to delete the plugin and reinstaled it but same problem.

Even when we turn of all plugins and just start with WP Cerber we get this error.

We got this message on one page

Fatal error: Uncaught Error: [] operator not supported for strings in /var/………/wp-content/plugins/wp-cerber/common.php:998 Stack trace:
#0 /var/………/wp-content/plugins/wp-cerber/cerber-load.php(4287): cerber_admin_message(‘<img style=”flo…’)
#1 /var/………/wp-includes/class-wp-hook.php(286): cerber_set_up(”) #2 /var/………/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(”, Array)
#3 /var/………/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #4 /var/………/wp-admin/plugins.php(180): do_action(‘activate_wp-cer…’)
#5 {main} thrown in /var/………/wp-content/plugins/wp-cerber/common.php on line 998

Hopefully somebody can help us.