Hi I also have Xiaomi Mi 10 Pro, I wanted to answer before but had an issue to make account, anyway you must root phone for this to work so I suggest backing up everything using twrp, then root and go to main android folder using a root explorer of some sort, main folder is just "/" open and edit "build.prop" file using a text editor, and remove the two lines mentioned above:
ro.config.media_vol_steps=30
ro.config.vc_call_vol_steps=14
then save and replace previous file and reboot phone this will fix this issue, then you can remove root or leave it enabled, it's up to you, I can confirm on my Mi 10 Pro that it works, if I didn't explain myself correctly please tell me I will help as best i can, sorry for any bad English and I hope this helps you, and the devs can implement this fix in next builds...