I have my RPI4 running @1850MHz and Airspy@ -e:8.6 with the following additions in config.txt:
force_turbo=1
over_voltage=4
arm_freq=1850
Running your oneliner will get me:
core: volt=0.9720V
sdram_c: volt=1.1000V
sdram_i: volt=1.1000V
sdram_p: volt=1.1000V