Apparently earth soaks up ~400-800 kg of aluminum oxide in cosmic dust each day.
So with 1-2 starlink satellites producing 30kg each dissipate each day, that's adding about 10% to this figure.
I'm not sure if the cosmic dust aluminum finds itself in the same places up there as the dissipating starlink aluminum. Maybe that could be figured out from the above paper.
This could have a significant effect, I don't know.
Are those ~400-800 kg of aluminum oxide in cosmic dust each day uniformly distributed, and if not how big are those clouds of aluminum oxide that the earth is travelling through? Those 30kg from the satellites are going to be extremely concentrated and therefore take longer to "soak up".
I wonder how much aluminum oxide we get though from disintegrating meteors and other impacts every day. Quick search suggests 50-100t of mass from meteors on average each day - similar total to the dust. Those might be more concentrated and analagous to the starlink satellites.