Manual:$wgManualRevertSearchRadius

Details
Maximum number of revisions of a page that will be checked against every new edit made to determine whether the edit was a manual revert.

Computational time required increases roughly linearly with this configuration variable.

Larger values will let you detect very deep reverts, but at the same time can give unexpected results (such as marking large amounts of edits as reverts) and may slow down the wiki slightly when saving new edits.

Setting this to 0 will disable the manual revert detection feature entirely.

The result of revert detection will be available via the parameter of the  hook, and the  parameter of the  hook.

See m:Research:Revert for a discussion on this topic.