Veeam One indicates unreasonably high values for highest latency on VMs (see screenshot below):
The same latency values can be observed in VI Client performance charts under disk/real-time during snapshot deletion. The values may also be negative.
This is a known behavior of VMware. KB 2001676 by VMware describes the behavior in more detail.
False alerting on Veeam side will be eliminated in the coming patch for Veeam One.