https://www.drupal.org/node/3257407
Use "content" region in BlockCreationTrait::placeBlock() instead of "sidebar_first" [#3257407] |...
Feb 17, 2022 - Problem/Motivation This came up in [#3219959]. BlockCreationTrait::placeBlock() places blocks in a sidebar_first region by default. Not all themes will have...
region inusecontent