Per Subbu: "Because of some performance-related fixes, Linter is now reporting estimated error counts instead of actual counts. Therefore, wikis might notice an artificial increase in error counts. Once we figure out a better solution to the performance problem, this will be fixed. [...] this only seems to affect wikis that have linter categories with large error counts." Keep an eye on https://phabricator.wikimedia.org/T184280: we appreciate your understanding.