To me it sounds like the mic position moved between the acceptab;le and un acceptable recordings. The unacceptable ones have way more “room” and i think this would be caused by the speaker moving away from, or the the mic being moved away from the source or moved off axis. .
Its wall refelctions.
Id also guess that the mic was pointing up over rather than dropped in from above, but of course i dont have the pictures.
Cant be removed to the best of my knowlege.
Adding music mask “mask” to some degree.
Peter
Post Production Dubbing Mixer