It will be something simple in your workflow. Do you still have the Gimp xcf with layers?
A quick remake, not trying to copy, might look like this with layers: https://i.imgur.com/jVNTfkn.jpg
All done with alpha-to-selection from the text layer, but there are semi-transparent (anti-aliased) pixels on the boundaries. Either have them for smoothness or suffer a jaggy edge.
If you do not have the original then I would dive in at a pixel level and paint in some repairs.
A quick remake, not trying to copy, might look like this with layers: https://i.imgur.com/jVNTfkn.jpg
All done with alpha-to-selection from the text layer, but there are semi-transparent (anti-aliased) pixels on the boundaries. Either have them for smoothness or suffer a jaggy edge.
If you do not have the original then I would dive in at a pixel level and paint in some repairs.