Jetpack: newsletter preview doesn't match frontend experience with OnyxPluse Theme

Using the theme OnyxPulse, I turned on the settings for a pop up to appear when scrolling down posts. I noticed the option to preview and edit so I made some customizations. At first glance, it appeared the background would be black and text white. Instead, on the front end of my site, the background was white on white text! Thankfully, I noticed that I hadn't set any local colors to the group block within the template part and added a black background with white text:

https://github.com/user-attachments/assets/33555362-e680-4f43-83e6-fee7493e0718

This is somewhat related to the following issues I think as it would help to know whether any color is being inherited at all: https://github.com/WordPress/gutenberg/issues/49278 I'm curious why the template part pulled this color in and whether that's something we can better display.

No file or test is named. Reproduce the newsletter popup preview and frontend behavior with the OnyxPulse theme, then inspect how the template part and group block determine inherited colors. Done means the preview and frontend render matching background and text colors, with the inheritance behavior clearly represented.

Written by the indexing model from the issue text.