Cage transform I would recommend to never use this Tool... for anything!
In your case
Filters ➤ Distorts ➤ Curve Bend...
It seems that you did used the Lower option only... which is the bottom of the text/image to curve (to amplify the effect, do a Layer ➤ Crop to content before opening the Curve Bend)
Add as many nodes as you need and move/drag them to smooth the curve
Result (after applying the effect your layer might be somewhere partially hidden, just use the move tool to bring it back where you want)
More ➤ https://docs.gimp.org/2.10/en/plug-in-curve-bend.html
In your case
Filters ➤ Distorts ➤ Curve Bend...
It seems that you did used the Lower option only... which is the bottom of the text/image to curve (to amplify the effect, do a Layer ➤ Crop to content before opening the Curve Bend)
Add as many nodes as you need and move/drag them to smooth the curve
Result (after applying the effect your layer might be somewhere partially hidden, just use the move tool to bring it back where you want)
More ➤ https://docs.gimp.org/2.10/en/plug-in-curve-bend.html