If your audio quality (both yours and the audio of other musicians) in a JamKazam session sounds good at the beginning of a session, but then deteriorates over time or suddenly changes during your session to sound wrong/bad all at once, the most likely cause is that your audio interface has lost sync with your computer's operating system, or that the audio interface of another musician in your session has lost sync with his/her computer's operating system.
If your own instrument and/or voice sounds wrong/bad, or if all of the audio in the session sounds wrong/bad, then it is very likely your own audio interface that has lost sync. In this case, we recommend that you click the Resync button (pictured below with arrow). This restarts your audio interface, and should restore your audio quality to where it started.
If your own audio sounds fine, but the audio of another musician in the session starts to sound wrong/bad, then we suggest that you ask that musician to click the Resync button in their own app - because that will restart their own audio interface, which is likely to have lost sync.
If this doesn't clear the problem, the next thing to try would be for either you (if your own audio or all audio sounds bad) - or another musician (if just their audio sounds bad) - to leave the session, close the JamKazam app - and then restart the app and re-join the session.
If none of these actions clear up the problem, then we'd suggest you refer to this help article on audio quality problems for additional troubleshooting steps.