In the last days, almost every change for AbuseFilter had at least one check randomly fail. To report some: https://gerrit.wikimedia.org/r/#/c/418716/ (which just had 2 fails in a row, both false positive and also with different reasons), https://gerrit.wikimedia.org/r/#/c/417842 (patch set 4), https://gerrit.wikimedia.org/r/#/c/417811/ (which failed 2 times gate-and-submit) and https://gerrit.wikimedia.org/r/#/c/418142/. These are only examples, but it's quite easy to find others. This only seems to happen since about a week, much more frequently than before.