Do I need a Drupal 9 upgrade?
Drupal releases updates to bring new features into its codebase and to remove deprecated or old code. Release cycles are published far in advance and the community will continue to support the most recent two release versions.
DRUPAL 7 END OF LIFE
If you’re running on Drupal 7 or 8, support will be phased out from November 2021. Earlier Drupal versions are already unsupported. Beware upgrading from Drupal 7 to Drupal 8 or 9 is complex as Drupal 8 included some major new features.
DRUPAL 8 - 9 UPGRADE
Fortunately, the upgrade path from Drupal 8 to Drupal 9 is relatively straightforward. At this stage it is anticipated that Drupal 9 will be supported until late 2023 with a Drupal 10 release taking place in mid 2022.