The definition is:

> In paragraph (1), a “content recommender system” means a system, used by the provider of a regulated user-to-user service in respect of the user-to-user part of that service, that uses algorithms which by means of machine learning or other techniques determines, or otherwise affects, the way in which regulated user-generated content of a user, whether alone or with other content, may be encountered by other users of the service.

Speculating wildly, I think a bunch of the moderation / patroller tools might count. They help to find revisions ("user-generated content") that need further review from other editors ("other users").

There's not much machine learning happening (https://www.mediawiki.org/wiki/ORES), but "other techniques" seems like it'd cover basically-anything up to and including "here's the list of revisions that have violated user-provided rules recently" (https://www.mediawiki.org/wiki/Extension:AbuseFilter).

(Disclaimer: I work for the WMF. I know literally nothing about this court case or how this law applies.)