Panel "Disk IO Size" on "OS/Disk Details" dashboard shows wrong data, multiplying average IO size by 512.
Since early 2018 Prometheus switched these metrics to actual bytes instead of sectors. See https://github.com/prometheus/node_exporter/blob/master/collector/diskstats_linux.go#L105 and https://github.com/prometheus/node_exporter/pull/787
Can be easily confirmed by running a FIO test on an otherwise-idle server.
This should (and does) generate a steady stream of 16kb-sized IO requests, but Disk IO Size will show a steady stream of 8mb-sized IO requests, or exactly 512 times larger.