I am seeing weird error messages "REPLACED INVALID CHAR SEQUENCE" and such when trying to display some logs in Security Logs:
Release : All Supported Clarity Releases
Component : CA PPM SAAS INSTALLATION AND UPGRADE
What you're seeing in the logs preview is due to the fact the logs are zipped (format is .gz) so the file is Binary and cannot be effectively previewed. To review the file you have to download and unzip it first. Then open with Text Editor.
The Security Logs page will only display text log files.