Valid point. From background research the general consensus is that impact of contrails is problematic, although the scale is debatable.
Google do have a website with some further info/Q&A at
https://sites.research.google/contrails/ which includes the following claim
Is there a risk that you cause more harm than good? You’re burning additional fuel - how do you know the additional fuel you’re burning isn’t worse than the contrails you’re mitigating?
Our teams spend a lot of time making sure we are having a net beneficial impact on the climate. When scaled up across an airline’s fleet, our results suggest that the additional fuel burn would be about 0.3%. Using numbers from the IPCC, the reduction in contrail warming is 20x greater than the additional CO2 from fuel burn