They observed an increase, but the statistical test they used couldn't distinguish it from noise with sufficient confidence to call it "statistically significan

They observed an increase, but the statistical test they used couldn't distinguish it from noise with sufficient confidence to call it "statistically significant." Statistical significance and a significant increase aren't the same. A statistically significant increase might be totally insignificant, and for a small enough study, a subjectively "significant" increase might be statistically insignificant.