Resolve #3210822 'Drupal 9 Deprecated report (against 8.x-1.0-rc18)'
The latest patch at https://www.drupal.org/project/h5p/issues/3150110 (https://www.drupal.org/files/issues/2020-07-09/3150110-drupal9_deprecated_report-7.patch) was applied to the latest RC (8.x-1.0-rc18) to make it Drupal 9 compatible.