in a short term view yes i agree, but its more than just starlink (we have all sorts of sat's made of highly refined materials falling from the sky), and its over years... decades even.
I haven't seen articles on this, so either its being ignored or it's not an issue. :-/
I strongly suspect it's the latter - since "Every day, Earth is bombarded with more than 100 tons of dust and sand-sized particles." [1] and the satellites burning up aren't going to approach that mass simply due to launch costs.
There is no uranium or plutonium in these satellites, nor anything else radioactive. On the other hand, according to [1] the abundances on this page multiplied by [2] 40000 tons per year, the stuff naturally hitting the atmosphere each year includes 0.3 kg uranium, 1.6 kg thorium, 3 kg radioactive isotopes of potassium, 10 kg mercury, 18 kg cadmium, 50 kg lead, 72 kg arsenic, and 120 tons of chromium, among other things. This stuff burns up in the atmosphere all day long, and has for billions of years.
Well Starlink will be the majority of all satellites pretty soon, so it really only matters for Starlink for the foreseeable future, if it matters at all.
I haven't seen articles on this, so either its being ignored or it's not an issue. :-/
I hope its the later.