On both blogs (energieagentur-obb.de, nachhaltigkeit-management.de) the plugin has been running for years without any problems. I have also not changed anything in the configuration. The temporal connection with the plugin update is a clear sign for me that something has changed.
to your questions:
(1) There is a active post notification campaign ‘New post published’ since 2020-04-26. Select post category = “all categories”
(2) The post on energieagentur-obb was a new post. The post on nachhaltigkeit-management was a cloned post
