From logstash on tegola codfw:
Dec 14, 2021 @ 19:55:27.961NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.960NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.918NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.913NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.911NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.910NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.909NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.909NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19 Dec 14, 2021 @ 19:55:27.908NOTICE 2021-12-14 19:55:27 [INFO] handle_map_layer_zxy.go:99: map (osm) has no layers, at zoom 19
It looks like tegola receives requests outside the kartotherian zoom range which is not expected.