When two broadcast channels are disabled, will the broadcast still be performed three times every broadcast event?

[OPQ]

In NRF5 SDK17.1, I disabled the Bluetooth broadcast channels 38 and 39 by configuring channel_mask. However, when I measured the broadcast current waveform, I found that there were still three transmit/receive pulses in the waveform. So, after I disabled channels 38 and 39, will the softdevice use channel 37 to broadcast three times by default?

[OPQ]

This's the measured current waveform after disable 38,39 channel.