I am also facing the same issue when I upgrade my project from Drupal 8.9 to 9.5 and I don't know how to fix it. When I run the update.php it gives the below error,
image module
Update image_loading_attribute
Failed: Drupal\Component\Plugin\Exception\PluginNotFoundException: The "default" plugin does not exist. Valid plugin IDs for Drupal\Core\Field\FormatterPluginManager are: address_default, address_plain, address_country_default, address_zone_default, comment_permalink, comment_username, comment_default, commerce_remote_id_default, commerce_plugin_item_default, commerce_order_item_table, commerce_order_total_summary, commerce_payment_method_profile, commerce_price_calculated, commerce_price_plain, commerce_price_default, commerce_product_attributes_overview, commerce_add_to_cart, commerce_usage_limit, commerce_store_datetime, datetime_time_ago, datetime_default, datetime_custom, datetime_plain, entity_reference_revisions_entity_view, file_link, file_extension, file_size, file_table, file_rss_enclosure, file_uri, file_default, file_audio, file_video, file_url_plain, file_filemime, fivestar_stars, fivestar_rating, fivestar_percentage, image_url, image, link_separate, link, list_default, list_key, state_transition_form, entity_reference_rss_category, text_summary_or_trimmed, text_trimmed, text_default, author, user_name, webform_entity_reference_url, webform_entity_reference_link, webform_entity_reference_entity_view, language, number_unformatted, entity_reference_entity_id, number_integer, uri_link, number_decimal, email_mailto, timestamp_ago, boolean, string, entity_reference_label, basic_string, entity_reference_entity_view, timestamp in Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition() (line 54 of /home/drupal/public_html/cms/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryTrait.php).
It shows the plugin does not exist but these all plugins exist in my project.
Patch #2 applied successfully on drupal version 10. It looks good to me
Thank you