https://www.orolia.com/resources/blog/lisa-perdue/2018/gps-2019-week-rollover-what-you-need-know

There is a GPS week number rollover event on April 6/7 2019. After
this date, some instruments might report the wrong date in an unpredictable
manner. In competitions this spring it might be necessary to have a temporary
measure to allow IGC files with the wrong date when a pilot's instrument is
shown to have that behaviour. After all, it is not an issue with identifying
which task is being attempted. The time and positions should remain correct. But
any GPS chip designed over about ten years ago might fail. And it is possible
that even newer instruments can be fitted with these older GPS chips.