Yes, I agree. I have actually also made a comment about this slew-rate resistor regarding the BTS7960 on the popular IBT_2 module:
https://forum.arduino.cc/t/bts7960-btn7960n-ibt-2-motor-drive-module/1142926/6
The slow slew rate cause very high switching losses with the BTS7960.
I have looked the Infineon datasheet on these kinds of integrated circuits, and this is my comparison:
You are right, the H-bridge output voltage becomes un-linear at lower pulse widths (my previous remark was wrong). I assume that it is similar when you have got three half bridges for control of a BLDC motor. I have made an example of that using the typical values for the BTS 7960:
Assume these preconditions for a brushed DC-motor with a four-quadrant H-bridge control (look previous link):
Power voltage: 24 VDC
Half H-bridge slew rate: 11 V/us
Triangle control frequency:10 kHz
Pulse period time: 50 us
Full shift time: 2.18 us
With some calculations, I see these idealized output voltage and changes by changing the pulse width:
Pulse width and the output mean calculated voltage
0.18 us 0,007 V
1.18 us 0.307 V
2.18 us 1.047 V
3.18 us 1.527 V
10 us 4.800 V
11 us 5.280 V
1 us change of pulse width and change of output voltage:
0.18 to 1.18 us 0.300 V
1.18 to 2.18 us 0.740 V
2.18 to 3.18 us 0.480 V
10 to 11 us 0.480 V
At low pulse widths you got an unilinear (parabola) behavior, and the increased amplification in parts of the range might cause instability.