Over about 6 weeks I could not see a single airliner over the whole sky during the heaviest phase - up to now - of the Covid-19 Lockdown. And even many weeks after this phase, there are still noticably fewer airliners visible.
Concerning astrophotography, stacking of many frames removes the airplane position light chains in affected frames. But I am wondering about this: can you quantify the rough number or percentage of frames which are totaly unaffected by airplanes during these Corona-times compared to pre-Corona-times? Do you even need less frames than usual to stack to get rid of unwanted stuff in the frames?