I have noticed some change in curve bend with recent versions of Gimp 2.10.x but for use in a script-fu, I have to go way back to Gimp 2.10.8 for the one-and-only script that uses curve-bend that I know of to work, RobA's curve-bend-between-paths
20 second demo https://i.imgur.com/inbjjUa.mp4
20 second demo https://i.imgur.com/inbjjUa.mp4