Hi,
If you miss the announcement:
https://www.php.net/archive/2019.php#id2019-06-13-1
Of course, if you want to test it, a SCL is already available
https://blog.remirepo.net/post/2019/05/22/PHP-7.4-as-Software-Collection
Most of extensions are already compatible, see
https://blog.remirepo.net/post/2019/05/23/PHP-extensions-status-with-upco...
So, time to start testing your packages with this new version.
Cheers,
Remi