I'll preface this with the fact that I've seen one similar post to this, but the reasoning for the other post was basically a direct violation of Spotify TOS and the real issues couldn't be further from that.
This issue with Spotify pausing while using Discord voice has gotten pretty crazy. I don't share my Spotify over Discord voice, nor does my mic pickup Spotify. If the A/C is on in the background, my fan, my server, someone else talking, if I talk for 30 seconds, if I accidentally leave my background noise limiter set to low and while noise is not audible it still registers something.
All of these scenarios and more lead me to have to disconnect my Spotify from my discord. I can no longer listen along and share music with my friends directly with the app because connecting my Spotify leads to constant adjustment and constant irritation with trying to figure out what is currently making my Spotify pause every 30 seconds.
Make it an option and leave it on by default if you must but if I'm in a gaming scenario and I'm talking constantly with someone and every 30 seconds I have to pop out of the game to turn my Spotify back on I'm going to go insane.
Until then I'm going to leave it disconnected and I'll think of this every time I see the annoying notification to link the two.