Mateusz Konieczny
https://www.openstreetmap.org/way/48457224 - either tagging here or https://wiki.openstreetmap.org/w/index.php?title=Tag:boundary%3Dadministrative should be updated

https://wiki.openstreetmap.org/w/index.php?title=Tag:boundary%3Dadministrative claims that admin_level=3 is unused in Czech Republic