Ok, we had an issue deleting data from a series. The delete just hung and never completed. I assumed this was not really possible on Influx. Perhaps this is an edge case.
Recently my colegue was testing some script and added some huge numbers on metric that is used for one of those reports. We had to delete those tests as customer complained that now his total invoice number jumped to trillions.
While it is indeed a rare occurence, it is also very slow.