find_paragraph_type_use.php

<?php

/**
 * Search use of a paragraph type in fields for nodes and paragraphs.
 */

const SEARCH_PARAGRAPH_TYPE = 'my_paragraph_type';

$field_manager = \Drupal::service('entity_field.manager');

$storage_definitions_node = $field_manager->getFieldStorageDefinitions('node');

$list_fields_paragraph = [];

foreach ($storage_definitions_node as $key => $storage_definition) {
  if ($storage_definition->getType() === 'entity_reference_revisions' && $storage_definition->getSetting("target_type") === "paragraph") {
    $list_fields_paragraph[$key] = $storage_definition;
  }

}

$types = \Drupal::entityTypeManager()->getStorage("node_type")->loadMultiple();


foreach ($types as $type) {
  $definitions = \Drupal::service('entity_field.manager')
    ->getFieldDefinitions('node', $type->id());
  $fields = array_intersect_key($definitions, $list_fields_paragraph);
  foreach ($fields as $field) {
    $handler_settings = $field->getSetting('handler_settings');

    if (in_array(SEARCH_PARAGRAPH_TYPE, $handler_settings['target_bundles'], true)) {
      ksm($type);
    }
  }


}

$storage_definitions_paragraph = $field_manager->getFieldStorageDefinitions('paragraph');

$list_fields_paragraph = [];

foreach ($storage_definitions_paragraph as $key => $storage_definition) {
  if ($storage_definition->getType() === 'entity_reference_revisions' && $storage_definition->getSetting("target_type") === "paragraph") {
    $list_fields_paragraph[$key] = $storage_definition;
  }
}

$types = \Drupal::entityTypeManager()
  ->getStorage("paragraphs_type")
  ->loadMultiple();


foreach ($types as $type) {
  $definitions = \Drupal::service('entity_field.manager')
    ->getFieldDefinitions('paragraph', $type->id());
  $fields = array_intersect_key($definitions, $list_fields_paragraph);
  foreach ($fields as $field) {
    $handler_settings = $field->getSetting('handler_settings');

    if (in_array(SEARCH_PARAGRAPH_TYPE, $handler_settings['target_bundles'], true)) {
      ksm($type);
    }
  }


}