@revk After having lost a few toots to @IceCubesApp and @tootapp and even @ivory due to merely switching between apps on my phone to check a fact that is elsewhere, let alone the bug you’re describing, I have discovered that @MonaApp is doing drafts right. It will auto-save a draft as you type it, so if iOS quits your app for whatever reason, getting your post back is a matter of three taps - new post, drafts, latest draft. You don’t even need to find the post you were replying to. It will also keep media attached to the draft if appropriate.
It also synchronises this between iPad, Mac, and phone, so I can draft the post on my Mac, then go to my phone and add the photo I haven’t synced off it yet.
And it will take one massive draft and split it into a thread, at sensible locations, with added (1/5) page markers.
I’m a convert, happily paying for the app.