Broadcom doesn't certify Operating System Level Patches.
Release : 10.4.x 20.2.x 21.2.x
Component : SPCCRT : Spectrum Certification
Broadcom will certify the product with Operating System Versions (Ex: Windows 2016, RHEL 7.x) not at patch level.
Patches need to be tested in Test Environment before applying on to the Production Environment.
Take necessary backups
SSdb backup
How to backup the the Archive Manager (DDM) database
https://knowledge.broadcom.com/external/article?articleId=46779
How to Backup and Restore CA Spectrum Reporting Manager Database .
https://knowledge.broadcom.com/external/article?articleId=40262
What is the best practice to make a complete backup copy of SPECTRUM?
https://knowledge.broadcom.com/external/article?articleId=52398
Backup custom folder
%SPECROOT%\custom from each box in your environment.
Gracefully shutdown the services before Upgrading or rebooting the server.
https://knowledge.broadcom.com/external/article/76397/how-to-start-and-stop-the-spectrum-ss-pr.html
Now you can apply the patches
Start the services.