I have a similar issue, but the custom header option isn’t working for me. Even though I have checked the box “Do not show title and excerpt in header” and checked the enable custom header and selected the first of the content layout options, I’m still getting the header image. If I delete the header image, I get a gray box even if I ask for no background. I would like to skip the header image on my blog page and insert a custom title in the custom header. I was able to do this before the Gutenberg update.
Here is an example of how I want it to look:
https://www.inductionheatingexperts.com/about-us/
This is what it currently looks like:
https://www.inductionheatingexperts.com/news/
Also, only on the news page, the background of the masthead is not white, rather it is gray. This is the only page with the problem, and you can see it by the fact that my logo has a white background. I can swap out the logo with a transparent one; however, this page’s masthead will still be different than every other page on the site.