That seems very strange,
so what you are describing, is when you want to pass you mash the pedal but the car just revs likes it’s in natural so instead of accelerating the car is decelerating?
I think traction control (aka fun control) is kicking in and killing your power.
Repeat what you are doing but with the DCT off, report back.
Garage Queen: 2005 Audi S4 4.2L V8, Vortech Supercharger, Vented CF Hood, PSS9 Coilovers, Sway-bars, RS4 brakes, Fast Intentions - Cat-less Downpipes & Full Exhaust, 505AWTQ
Daily Driver: E92 335i N54: JB4 G5 ISO28 w/BMS Flash, quaife LSD, BMS Meth, AA sport IC, BMS Charge Pipe, BMS OCC, Euro Light Switch, M-Sport Kit; 12.1@117mph (stock intake stock exhaust, 225ís RFT)