It's due to be EOL'd in November 2020, per https://www.mediawiki.org/wiki/Version_lifecycle. It's November 2020, so...
Probably not to be done till the end of the month. And maybe get T264906: 1.35.1 Maintenance Release? out first?
As per the MediaWiki version lifecycle,[1] I would like to announce the formal end of life (EOL) of MediaWiki 1.34 as of today, Monday November 30, 2020. This means that MediaWiki 1.34 will no longer receive maintenance or security backports. It is therefore strongly discouraged that you continue to use it. It is recommended to upgrade to MediaWiki 1.35, the current Long Term Support (LTS) version which is not due to become EOL until September 2023. The legacy Long Term Support version of MediaWiki, MediaWiki 1.31, is older and downgrading is not supported. MediaWiki 1.35 bumps the required PHP version from 7.2.9 in 1.34 (which is unsupported upstream), to PHP 7.3.19 or later. Thanks! Sam Reed [1] https://www.mediawiki.org/wiki/Version_lifecycle