Sorry, it’s not Flowfact or Timber after all. The error occurs when in Timber (whether in the template or in functions.php) on a WP option page created with ACF is accessed.
As soon as the following code is loaded somewhere, it seems that the detail view of a property lands in a timeout and the loading time is over a minute.
For example with: $context['options'] = get_fields('option');
If someone has an idea what this can be, I would be happy about an answer. I will close this ticket for now.