Joomla 3 will loose security support end of August 2023. This means: it is time to upgrade Your website. But not only for security reasons.
Joomla 4 brings a lot of technical improvements: The web performance is faster and the included search engine works much better.
The fundaments for an improved API development are included. And coming PHP versions will be no problem.
But the migration is not so easy, especially if you have some specialties: an individual template, a special navigation, complicated forms etc. The website should be migrated cautious. On the other hand: This is the time for cleaning up, getting rid of unused tools and extensions - and implementing of new ideas for layout and interaction.
We are quite experienced in migrations meanwhile and prepared to help You.