You are definitely not alone with this - the Me too count on your post shows others are experiencing the same thing, and this is a known compatibility issue between the AirPods Pro 3 firmware and iOS 26 on the iPhone 17 Pro specifically.
The fact that it happens during active audio sessions like phone calls and Spotify rather than randomly in silence is a strong clue. What is happening is that iOS 26 is occasionally switching the AirPods Pro 3 to a lower-power Bluetooth mode (SCO/eSCO for calls or a rebuffering state for streaming), and during that mode transition the connection drops instead of seamlessly switching. This is a firmware/OS layer issue.
Since you have already done the main troubleshooting steps, here are a few additional things to try that are more targeted:
For the Spotify issue specifically, go into the Spotify app settings and look for the audio quality options. Lowering the streaming quality from Very High to High or Normal can sometimes prevent the buffer underruns that trigger the disconnect. This is a temporary workaround but it helps confirm whether streaming bitrate is a factor.
For phone calls, try going to Settings > Phone > Calls on Other Devices and disable calling on all other devices. If the iPhone is simultaneously trying to manage call routing to multiple linked devices, it can interfere with the AirPods connection.
Also check Settings > Privacy & Security > Bluetooth and look through the list for any apps that may have Bluetooth access enabled but should not need it. Rogue background Bluetooth activity from apps can interfere with the AirPods session.
Apple is aware of Bluetooth audio stability issues with the AirPods Pro 3 on iOS 26 and has been patching them in point releases. Keep your iPhone and AirPods firmware current and this should improve over the next few updates.
