Destiñendo comes from the verb desteñir, which means to fade in color, to lose its dye, or to bleed (like colors in laundry).
In the song, Daniela Spalla sings about "Tantas flores que están destiñendo" (So many flowers that are fading). This word beautifully captures the imagery of things losing their vibrancy and life, mirroring the fading of a relationship and the singer's emotions. It's a more specific and evocative word than a general term for 'fading'.
"Insomnio" is Daniela Spalla singing through the hours right after a breakup, the ones where nothing distracts you and everything in the room starts to feel like evidence. She opens on things going bad: "Tus discos se están derritiendo" ["Your records are melting"], flowers fading, photos she can't put her hands on anymore. None of that is really about the records. It's about how long it's been since anyone touched that corner of the apartment.
The chorus says the real thing out loud: "Ya no es tu ausencia, es mi indiferencia" ["It's not your absence anymore, it's my indifference"]. That's the whole song in one line. She isn't grieving him, she's unsettled by how little she feels. The "insomnio de casi dos meses" ["insomnia of almost two months"] she describes isn't romantic sleeplessness, it's just her body stuck on a schedule nobody else keeps, awake at odd hours for a reason that stopped making sense weeks ago.