Drupal 8 : Get a config settings value being stored in blocs
You need to load the block if your outside of the class, for that you need it's id.

$block = \Drupal\block\Entity\Block::load($bid);
$my_stored_value = $block-&gt;get('settings')['submit_action_amu_dud_form_block_settings'];


The id can be found in it's annotation if it's custom: @Block( * id = "my_fancy_block_id". If there are several instances of the block this may be altered and can be looked up in the DB, or the block config admin section - check the urls there.