Audio bitrate on HDMI?

I have connected the hdmi output of the Raspberry Pi 4 B (volumio 2.917) to a hdmi switch (to switch between Raspberry, DVB-S and notebook) and an audio extractor. The audio extractor, which supports bitrates up to 96 kHz, is connected via S/PDIF coax to my PS Audio Gain Cell DAC.

While playing flac, the DAC always shows a bitrate of 48 kHz.
Is it possible, to get the native bitrate like 44.1 kHz or even resampled to 96 kHz?
The settings in volumio are: DSD direct, no mixer for volume, audio resampling off or 24 bit @ 96 kHz.

Is there still a limitation of the bitrate as described in an older thread Raspberry Pi and HDMI Sample Rates ?