Each release branch of PHP is fully supported for two years from its initial
stable release. During this period, bugs and security issues that have been
reported are fixed and are released in regular point releases.
After this two year period of active support, each branch is then supported
for an additional year for critical security issues only. Releases during
this period are made on an as-needed basis: there may be multiple point
releases, or none, depending on the number of reports....
As of November 28, 2022, PHP 7.4 will no longer be supported by the PHP community.