Great Another Quick update
nothing serious in it, happened twice with my device too
just hold power + volume up + volume down untill you hear vibration it will boot normally
mounting issue is Persistent with old recovery. try latest recovery which shows internal storage.
also you can use thumb drive via otg.
flash latest Twrp with usb OTG
ohh then kindly also report this bug
probably no but you can use lawnchair from playstore it's exact replica with much more features
check whether force over ride option is off in developer settings.
that sometimes creates such situations
also select " force over ride dark mode" from developer options of you want all apps to keep dark accent
k20 Pro also recieved update before OnePlus. or say not just OnePlus were updated on same time
any screenshot how desktop mode looks?
select 3 dots on right hand side and open in browser to download
it needs to be downloaded and installed no ota
the suggestion appear only if person ask questions or the answer is yes or no types.
also you can check notification bubble is on or not from...
it won't erase probably as OnePlus said but take a backup in case anything bad happens