Ok, I got time to read it. Drones are only mentioned in one paragraph of the conclusion. Here it is:

‘Eco-friendly’ fireworks, which do not use perchlorate and have lower levels of heavy metals, do exist (Fan et al. 2021); the problem lies in their higher cost of manufac- turing (Palaneeswari and Muthulakshmi 2012). The future of ‘firework’ displays may lie in the use of drones or unmanned aerial vehicles. Drones and visible-wavelength lasers for light shows have the benefit of being reusable, have no emissions, and are quiet (Daukantas 2010; Zerlenga et al. 2021). Drones come with their own issues for wildlife, however, usually flying at low altitudes where there are most likely to come into contact with wildlife; a review indicated that many taxa react negatively to the presence of a drone (Rebolo-Ifrán et al. 2019). Even so, drone light shows are less likely to disturb animals, wild or domestic, with noise, nor do they deposit large amounts of pollutants.

The use of drones is an opening hypothesis, not the subject of the study. Impact of drones is not quantified, it is hypothesized to be lower. The linked papers that I have also checked also don’t quantify the impact but similarly mention it as a potential eco-friendly alternative.

Would you have a different reading of this article?