1000s of satellites are irrelevant to atmospheric pollution. The numbers are so small compared to the vast size of the atmosphere it isn’t really a concern to worry about.
Atmospheric pollution from earth based sources is different because it’s something that is being done in the scale of billions of people, not 1000s, and CO2 doesn’t naturally disappear from the atmosphere over time and is growing decade after decade.
Over one hundred metric tons of space dust falls on the earth daily. Do you really think SpaceX de-orbiting a 200 Kg satellite once a day or so is going to change that significantly?
Oh cool, let's shoot even more soon-to-obsolete pollution into the atmosphere. That's working so well on Earth. /s