According to the mailing list, Ubuntu 21.10 will transition from PHP 7.4 to PHP 8.0. Although PHP 8.0 was released at the end of last year, it was not immediately added to Ubuntu 21.04 at the time, considering a large number of changes compared to PHP 7.4, the Ubuntu dev team postpone the PHP 8.0 update plan to Ubuntu 21.10. This change ensures that PHP 8.0 is stable during the Ubuntu 22.04 LTS cycle.
At the same time, it will be updated a few months after the release of PHP 8.0, which allows PHP developers of Ubuntu 21.10 to solve more PHP codes that are not compatible with PHP 8, and perform more tests and bugs fixes. Currently, the transition has begun, PHP 8.0 has been pulled in from Debian Experimental and set as the default PHP. In the next few weeks, other components of the PHP stack may be rebuilt and updated to PHP 8.0 in other ways.
It is reported that PHP 8.1 with more new features is expected to be released at the end of this year, and may be used in the Ubuntu 22.04 LTS version next spring.