I just found out something chocking. Only 0,3 % of Joomla sites are using Joomla 4 and 5 (3000 sites totally). 84 % is using Joomla 3, Joomla 2 9,4 % and Joomla 1 6,7 %. People can avoid upgrade of Joomla to avoid changing a lot of extensions. It is not only to upgrade Joomla. My own guess...