Generally, you can trust the Power Quality results. But there have been a few occurrences of Power Quality giving erratic spikes. You might want to try a reboot as this user did:
Two other suggestions:
You might want to ask your electrician how your townhouse is wired. Single family homes are generally single split-phase, but apartments, condos and clusters of townhomes, especially with adjacent meters, are often wired via a three-phase supply, something that should still work with Sense, but worth knowing as you pursue this potential issue.
If a reboot doesn’t change things or if it does, but only does so for a short while, then consider checking in with Sense support. See @JamesDrewAtSense ’s message here: