I thought they start at about 250 km after launch and then boost up to around 400 km. They don't have very powerful thrusters or gyros so they couldn't boost fa

I thought they start at about 250 km after launch and then boost up to around 400 km. They don't have very powerful thrusters or gyros so they couldn't boost faster then they fell out of orbit. It seems that they are far safer once they have boosted up into operational orbit - that's why only the recently launched Starlinks fell back to earth.