Ringer and alerts volume too loud when using Airplay
I have an iPhone 11, running iOS 14.4.
When I have my phone connected to an Airplay device (specifically an Airport Express) to play music through attached speakers, the ringer and alerts volume is extremely loud. It sounds as if it is as high as it will go.
However, I have my ringer and alerts volume set below half volume. I have confirmed this in Settings>Sounds & Haptics immediately after noticing this issue, as well as in Control Center when my phone is not connected to Airplay.
When I am not connected to Airplay, my ringer and alerts volume plays at the level I have it set to.
Also, the ringer and alert volume does not match my Airplay volume setting. I usually keep my Airplay volume just above half, but as I said earlier, the ringer and alerts volume seems like it is playing at full volume.
If this happens when my phone is near me it is so loud it hurts my ears and is extremely startling.
This issue has persisted since at least late iOS 13. I have tried restarting my phone, adjusting the volume slider in Settings and adjusting the volume slider in Control Center, all to no avail. I have searched through the Settings app and have not found any other relevant settings that might resolve this issue.
iPhone 11