Please verify if setting Rpar of Inductor to 0 can resolve your problem. LTspice and Qspice define default parasitic differently. Inductor in LTspice in default with 1mohm series resistance (Rser) and in Qspice in default with parallel resistance (Rpar) = Inductance/15.91/Gmin
Unfortunately, your circuit is sensitive to parallel resistance and that cause the difference. Force Rpar=0 by add this as attribute and see if this is the result you are looking for.
There are different ways to force Rpar=0. Beside of individually add this, you can set .option LFT to infinite value (set LFT=1e308 or 0 can force this value to very large number).
You can goto Qspice HELP for more information. Or, you can goto L. Inductor section in my device guideline which can be found in this location
Qspice/Guideline at main · KSKelvin-Github/Qspice · GitHub
ButterworthFilter_18333.qsch (6.2 KB)
