Seems unlikely, a lot of foods have vitamin C. A quick google for vitamins and minerals in spinach suggests the contents are good (hmm, good for iron, maybe _I_ should eat it more often). 'Hypo' means different things in different contexts - below 5.0 for driving, more generally below 4.0.
I'm a Type 1, if the reported level (I now prefer to say 'predicted' level) is over, say, 14 there is about a 50% chance that it agrees enough with a blood test 3 minutes later, and about a 50% chance that it is much higher.
For predicted levels below 5 I find a much greater likelihood that it is giving a result way below the blood sugar level.
I've never knowingly seen a low reading which is higher than it should be, but I don't usually test if the prediction is in the range from 5 to, say, 14. One of the "targets" when I was admitted to the local libre2 trial was to reduce the number of test strips prescribed.
I also find that when I look at the logbook, if I have scanned and got a reading it might later show as above or below the graph. I've seen one or two high readings where I didn't need to scan (sensor was talking to the phone without a problem) and later there was no sign of such a reading.