Modify wp_installed_email / wp_new_blog_notification

I found a solution:
mu-plugins.
My code isn’t executed in this early state, but that’s what mu-plugins are for.
https://wordpress.org/support/article/must-use-plugins/
This did the trick.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)