Seems as if Apple has ironed out some nasty glitches and
bugs with their newest iOS release. Among the security flaw
of the parental control app to allow children to add new
contacts without the security code they also solved audio issues

Especially CarPlay users have probably had problems with distortion-free audio playback from their iDevice which should now no longer happen.

Another annoying bug was the loading of images in eMails via the Apple Mail app. Images are commonly used for tracking the user and if the mail has been read. A technique often used to verify if an email address can be used for spamming later on. Now it should no longer happen that external images get loaded in the Mail app.

With the rollout of iOS 13.3.1 also tvOS 13.3.1 and WatchOS 6.1.3 have been rolled out.

The Mac users can also update Catalina to 10.15.3 now