almost all the clients on the web do this, some worse than others

coracle's compose field remembers if you accidentally unselect it in a reply but once you change context it forgets also

the main compose button , now post+ up the top right, idk if it remembers prior inputs, probably not

primals is really easy to drop out of the input field and then poof it's gone

ah yeah, i don't really use any others, they are all shit xD