Pall of Gloom needs to be removable in some way

[Pantagruel]

You can remove other sources of gloom (altar of marching gloom, infestations) by destroying the source, but pall of gloom has no source and thus can't be removed, turning it into a large permanent penalty if cast on a city's territory.

[FuzzyJay]

Restore the land from the nature tomes can restore uninhabitable land back to grassland, hope that helps🫡