Changing Contacts background colour on MacBook Pro running Tahoe 26.0.1

I just upgraded to Tahoe Ver 26.0.1 on my MacBook Pro M4 Max / 64GB.

Here are the issues I am facing in the revamped Contacts App

1. Unable to change the background colour in the right pane which shows the Preview of the selected Contact (the vignetting bluish-purplish colour is a huge strain on the eye.
2. Unable to see the first few lines of the Notes (when I scroll down), especially when it contains Credit Card Numbers. Once I click on Edit, I can see the full notes.

These issues were not there in earlier OS.

Thanks in advance...

[Edited by Moderator]