UCC2819A: ZEROPOWER comparator

VAI external connection is assumed with a reference voltage > 0.5V, and typical should be tie to pin 9. If it is tied to 0 volt, the internal voltage error opamp cannot work normally, for one reason this error opamp is single polarity biased so cannot detect negative voltage, so noise will make pulses. For another, this pin needs a correct bias current while with zero voltage, this pin cannot be biased correctly so cannot be functioned correctly. The pulses at output can be generated in uncontrolled manner.

In short, VAI set up at 0 volt is not a valid setup and the associated test does not make the IC work normally so the observation does not provide any meaningful help to your noise issue resolution.