I found the change that was preventing authentication and updated the plugin with a workaround. Here is a new version that is working as of 07/13/2021 - SXM_Bolt_On V1.2.A.
This is the dropbox link to the updated plugin:
https://www.dropbox.com/s/m42ocl717p73p ... n.zip?dl=0Be sure to use the download function on the right side of the dropbox screen (under the three ... / more menu) as this will keep the plugin file format in tact to your download folder.
Once installed you will be able to tell if you are running the current version by this series of log messages:
Sonos: Initialized: SXM_Bolt_On V1.2.A
Sonos Doing this bit WITH initial load of website data
Sonos your_id_here <== This is the username from the init_chan_array function that was used to login to SiriusXM
Sonos [Tue Jul 13 17:15:29 2021] Processed plugin preferences.