Hi, please read about four wire fans here. They are a bit special.

https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans

Here's an example of one that I have:

; ================================== ; MCU fan ; ================================== M950 F2 C"!0.out4+0.out4.tach" Q25000 ; create fan 2 on pin out4 and set its frequency M106 P2 H3:4 L0.2 X1.0 T30:50 C"Controller fan 1" ; controlled by Sensor 3 - MCU

Please note that the standard pwm frequence of four wire fans is 25kHz.

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I can't say that Noctua isn't doing their own thing here but this is the way you normally configure four wire fans AFAIK.
https://www.electroschematics.com/4-wire-pc-fan/