Indeed, the color of dusk in combination with the clarinet, organ and trumpet ambients have made this mission quite unique and it emphasized the whole mystery, in my opinion. Without the orange tint and the instruments this would've still been a great city mission, but here nicked has crafted an absolute masterpiece I won't forget anytime soon!
Haha, it never bothered me while playing the mission but now that you've mentioned it I can understand why some might find it jarring on a replay. Personally I like it because it reminds me of the Disco Elysium OST 'Instrument of Surrender' by Sea Power. But if it's an issue for you then you can just delete clarinet[1-6].ogg from the mission's snd\ambient directory or replace the tracks with something else ^^