@apps Why not use a standalone "page" for image and image description under it (scroll), to use all the available screen space, instead on a popup? Just like "Compose a new post" has it's own page.
Save/keep current text to post => open description page => go back to current post/written content when Image description is saved.
With the current popup, it's way too small. See screenshot
And by current, I mean the latest version available on F-droid, I updated Fedilab a fes days ago