The issue has resurfaced, with focus being lost again. FocusMonitor.exe indicates that the Norton UI is still the culprit stealing focus. I investigated further and noticed in Norton that my system was pending a restart to complete the installation of the latest Norton Security version (25.12.10659). I went ahead and restarted my system, and so far I have not observed any further issues.
My theory is as follows: after I uploaded the logs to support, Norton likely provided an interim patch or fix to address the focus issue, which was pushed automatically - possibly through LiveUpdate. When the new Norton version (25.12.10659) was released, that interim patch may have been reverted or overridden before somehow, causing the issue to reappear. Hopefully, this has now been fully resolved in the new version that was applied after the restart.
Overall, I like and trust the team at Norton. After all, I am entrusting them with my system security and data privacy, and they are a well-established and reputable company. That said, I do wish issues like this were resolved earlier, with greater transparency, and without recurring, as repeated incidents can be quite frustrating and stressful for users like us.
That said, everything seems good now, and I am hopeful this remains resolved.