Gimp 2.10.24 Export window too large.

[Ofnuts]

In my version of Gimp the size of the export dialog appears to be saved between Gimp sessions. So either:

• Your Gimp is set up to save window positions on exit, just resize the dialog and that should do it
  
• Your Gimp is set up to fixed window positions, then start Gimp, do a dummy export, resize the dialog, and before exiting Gimp, go to Edit ➤ Preferences ➤ Interface ➤ Window management ➤ Window positions and hit the Save windows positions now button.
  

See here for some more hints.