As per https://www.mediawiki.org/wiki/Version_lifecycle
Using https://lists.wikimedia.org/pipermail/mediawiki-announce/2020-January/000245.html as a base
As per the MediaWiki version life cycle , I would like to announce the formal end of life (EOL) of MediaWiki 1.33 as of next week, Tuesday June 30, 2020.
This means that MediaWiki 1.33 will no longer receive maintenance or security backports (barring an unforseen issues with the 1.33.4 release today). It is therefore strongly discouraged that you continue to use it.
It is recommended to upgrade to MediaWiki 1.34 (due to become EOL in November 2020). The current Long Term Support (LTS) version of MediaWiki, MediaWiki 1.31, is however older (and downgrading is not supported. The delayed next LTS (MediaWiki 1.35) is currently due to be released in early August 2020, and will be supported until at least June 2023.
MediaWiki 1.34 bumps the required PHP version from 7.0 in 1.33 (which is unsupported upstream), to PHP 7.2.9 or later.