A fix will be available shortly. There is no data stored in the files or ever written to disk via these files, they are used to create a temporary shared memory segment for communication between the audio client in each child process and the audio server in the parent process.
As a temporary workaround, you can disable the audio sandboxing feature by setting media.cubeb.sandbox in about
:config to false. You'll need revert the preference to the default value once a fix is available to restore full functionality.