Description
Since WordPress v6.7 notices like this are thrown when translations are used to early in the loading sequence.
Notice: Function _load_textdomain_just_in_time was called incorrectly. Translation loading for the post-smtp domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /app/public/wp-includes/functions.php on line 6114
So currently it is impossible to update WordPress to a version >6.2.2 when debugging and display errors is enabled (what usually should in all development and test stages).
The changes in the beta v3.0.1 don't solve the problem. For further details see https://wordpress.org/support/topic/translation-loading-for-the-post-smtp-domain-was-triggered-too-early/