Joomla is a beautifully matured CMS, and long term Joomlers might knowingly nod, when I say it was a bumpy ride at times. Have a look at this article 'Celebrating Joomla 4' to get an idea of the new features of Joomla 4.
If you are (relatively) new to Joomla, chances are your website uses a template compatible with Joomla 4 (or at least your template developer provides a fully J4 compatible version of the template). Then you are lucky and this article is of no concern for you. But what if your website has been running for years now, and you are considering a migration from Joomla 3 to Joomla 4?