I'm starting a new post since I don't seem to be able to reply to the others I have found here. This is a long standing issue that I have patiently been awaiting a fix for, and based on numerous other posts on here I'm not alone.
Spotify continues to sporadically begin playing back at what sounds like double the speed it should. Sometimes force stopping the app and reopening it temporarily corrects this behavior. Sometimes restarting the device temporarily corrects this behavior. Sometimes completely removing and reinstalling the app temporarily corrects this behavior. The key word here is "temporarily" because it always returns.
I use Spotify on several devices including Android, iOS, Windows, Linux, and Google Home to name a few. This issue has occurred on all of them several times over the course of my subscription. It occurs both with and without using bluetooth headphones or other peripherals. I have noticed that it does seem to occur only over wireless connections, at least in my case.
My most recent experience with this occurred just a little while ago. I was playing back an episode of a horror podcast that I had previously downloaded when mid-sentence the tone of the story went from creepy to full on Chipmunk extravaganza. At this point, all sound coming from Spotify was being ran through the Chipmunk filter. Other music and sounds coming from the device were fine.
What I did to correct it this time was to remove the downloaded episode, then play the same episode for a moment, after which everything started playing back correctly again. This makes me suspect that the original download was corrupt in some way and caused the issue.
I'm not an expert on the subject, but this would seem to fit with the other "solutions" people have found for this issue. Restarting the app or device could easily be clearing corrupt cached content, and completely reinstalling the app definitely would.