Starlink satellites mass 300 kg each. There's about 5000 of them in orbit, so that's 1,500,000 kg.
The Earth has about 5.15x10^18 kg of atmosphere. 5,130,000,000,000,000,000 kg of gas. If each satellite aerosolized completely (which it wouldn't, metals would rapidly precipitate out of the air) then they would make up a couple parts per trillion of the atmosphere. Way lower concentrations than cloud seeding.
In contrast, routine operations of Air Force One emit around 41,000,000 kg of CO2 per year. (They fly not just the president, but his security detail, and the presidential limo to every foreign visit)
